For some reason, the slider often comes off old or shoddy zippers, and there is no way to put it back on. The first method will not damage the fabric, but it may damage the zipper, the second method saves the zipper at the expense of the fabric.
Steps
Method 1 of 6: Using the Pliers

Step 1. Align the two sides of the zipper as best you can
The best way to do this is on a flat surface.

Step 2. Insert the teeth on the open side into the slider as much as you can

Step 3. Using a pair of pliers (so that the inside of the pliers touch the outside of the slider), thread the open side of the zipper into the slider
The open side of the zipper should now be almost entirely inside the slider.

Step 4. Slide the slider up and down to see if the zipper re-attaches itself
If not, then slide the slider as close to the end as possible. The end should be where you would start to close the zipper.

Step 5. Position the pliers so that the inside touches the top and bottom of the slider
Drop the pliers down until the detached side returns to its place.

Step 6. You may need to move the pliers from the sides of the slider to the top and bottom until the hinge is fully reattached

Step 7. When you are done, you will not be able to open the zipper past the point where you forced the detached side back into the slider, as you will have damaged several teeth on the other side
Method 2 of 6: Using Scissors

Step 1. Look at the broken zipper
The slider is still inserted on one of the two sides, while the other has slipped off. There is an up direction (the direction you use to close the zipper), and a down direction.

Step 2. With a good pair of scissors, make a cut on the side of the zipper that does not have the slider, at the same height as the end of the slider when it is positioned as low as possible
Make the cut between two zipper teeth.

Step 3. Slip the open side of the zipper over the top of the slider where you made the cut

Step 4. Slide the slider all the way to the top until it can no longer climb
The cut side may be a little flawed. If it is so…

Step 5. Open the two sides of the zipper so that you have two separate parts under the slider

Step 6. Pull the side of the zipper where you made the cut down to make the blemish at the top of the zipper disappear
You may have to pull hard.

Step 7. Put some adhesive on top of the cut, and on the zipper below the cut to keep it together
You will not be able to lower the zipper past this point.
Method 3 of 6: Use a Nurse Pin

Step 1. Use a safety pin to hold the two separate parts together
Method 4 of 6: Use a Screwdriver

Step 1. Insert a slotted screwdriver into the side of the slider where the zipper is locked

Step 2. Place it on a solid surface, and gently tap the top of the screwdriver to open the slider (note this only works with metal sliders)

Step 3. Place the slider over the zipper, and using a little force slide it up or down until the slider slides over the zipper

Step 4. Now, using a pair of pliers close the slider
Don't use too much pressure as you could break the slider.
Method 5 of 6: Alter the Zipper
If the slider has come off the zipper and the zipper is closed, you can reinsert the slider by sacrificing a piece of the zipper.

Step 1. Just separate the ends of the zipper (about 5-6 teeth)
You can re-engage your teeth if too many open at first.

Step 2. If you can find a suitable tool, take one of the two open sides of the zipper and cut off the 5-6 teeth you separated
The end of the zipper can no longer be closed.

Step 3. Hold the ends together again and start threading the slider again
In this way, the joined ends are threaded into the narrowest part of the slider.

Step 4. Keep pulling on the zipper and it should start to separate inside the slider due to the cut you made

Step 5. If you keep pulling, the slider should move over the rest of the zipper and separate the zipper properly

Step 6. Use a safety pin or similar material to fix the zipper and lock the slider the next time you close the zipper
Method 6 of 6: Bag or Cosmetic Bag (for Accessories)
If it is a simple zipper that opens something, and that does not have a main side (such as happens in pants), you can try this method.

Step 1. Simply put the cursor in reverse

Step 2. Pull it up to the top

Step 3. Sew the two flaps together behind the slider so that it doesn't come off again
Advice
You may damage the zipper when you pull it to reduce the blemish on top. You could also make the cut (in step 2) at the height of the end of the slider to minimize the difference
Warnings
- Using method 4 you could injure your hand if the screwdriver slips off the slider.
-
Method 1:
- Using pliers could irreparably damage the cursor.
- Using pliers to force the detached side back into the slider will damage the teeth on the attached side. You won't be able to open the zipper beyond where you reattached it.
-
Method 2:
- Only do this if you don't want to ruin the fabric. If it has enough value that you don't want to take the risk, consider changing the zipper.
- It does not work with zips that should open fully, like in jackets. Also consider that in this case the cursor MUST slide completely out of one of the two sides, so you don't need to read this article …