Can I get my camera lens repaired for free?

Question

I don't have the receipt anymore but I do have the warranty paper.

Answer 1

Maybe you registered your lens at time of purchase.  As long as you did, the serial number on the lens would be enough to get the warranty repair.

Answer 2

It depends ... some lenses have one year warranties, some three and others like Nikon, five year warranties.  Unless your lens was damaged, any problems that have to do with the workmanship while assembling the lens are fully covered up to the end of your lenses warranty period.