The T3i and it's kit lens are not weather sealed from water spray or dust -- so take reasonable precautions when bringing it along to the beach (Canon's does have bodies and lenses which are weather sealed, but the Rebel series doesn't include it.)
It may be repairable but Canon would probably have to evaluate it (you'd probably have to send it in -- they can't know why it's not working without getting into it.)
Depending on the lens and the extent of necessary repairs, it may be less expensive to buy a new lens. If this is the EF-S 18-55mm f/3.5-5.6 IS II kit lens that comes with a T3i when purchased as a body/lens kit, then the new EF-S 18-55mm f/3.5-5.6 IS STM lens is a nice upgrade over the original.
If you are trying to keep costs low, check Canon's "refurb" section of their online store. You can find it here: http://shop.usa.canon.com/shop/en/catalog/lenses-flashes/refurbished-lenses
Note that the inventory of Canon's refurb store changes all the time -- the lens you want may not be available. You can also check used prices... some well-known retailers sell used gear and check-out the condition of the gear and provide a fair "grade" of it's condition in their description so you have an idea if the lens looks new, lightly used... or really beat up (I think they even have a grade which says it's non-working and useful for 'parts only').
Tim Campbell
5D III, 5D IV, 60Da
