This lens can sometimes be disassembled and reassembled, and there are unofficial teardown guides online that may help if you have the tools and experience. However, when the front section falls out on the EF 50mm f/1.8 II, it often means an internal plastic part or retaining piece has broken. If that’s the case, simply snapping it back together may not fix it, and replacement parts may be hard to find.

In practice, your options are:

• Try a careful DIY repair only if you’re comfortable disassembling lenses.
• Check whether anything is visibly broken or loose inside before reassembly.
• Consider replacement instead of paid service, since professional repair may cost more than the lens is worth.

So yes, it may be repairable, but only as a DIY attempt with no guarantee of success. If internal parts are broken, replacing the lens is usually the more practical solution.