Depends on what you want to do, those are like 30$ right? It's totally understandable that some people don't have that much to spare, I certainly remember when I didn't have 20$ in my pocket, but the best option would just be to buy something else, even something like a Samson sr850 or any other chear over-ear like that would not only be a massive improvement in sound but not break the bank at 50-60$(cad)

If you were to fix it though, I'd recommend going out and getting super glue, some rubber bands to hold it and some clips to to the same while it's drying and then just lather it in glue and hope it sticks

All in all for the price of super clue and tape and clips though you could probably just get a set of headphones that matches the quality of your current pair at least