I've heard that drying in an oven, or using a hair dryier on low works for some people. Putting it in a box with a fresh silica dessicant could help, or burrying it in some fresh rice can help extract remnant water. If the phone ends up working, but the keys do not, it could be that just one of the connectors in the phone is corroded. These can be cleaned.
Generally, the keypad does not need to be changed. Usually, one of the flex connectors in the flip (screen/camera) portion of the phone is loose, dirty and/or corroded (maybe from water, sweat, wear, trauma, etc). This is relatively easily fixed by a semi tech savy consumer. You will need a size T5 star driver (and possibly a T6) and a small screw driver, along with some rubbing (isopropyl) alcohol and some Q-tips.
For more information on servicing your phone, you should do an internte search for RAZR dissassembly http://www.google.com/search?sourceid=navclient&aq=t&ie=UTF-8&rls=GGLJ,GGLJ:2006 -45,GGLJ:en&q=razr+v3+disassembly
and you'll get lots of hits including videos like this: http://video.google.com/videoplay?docid=-5120755491924318860
When you have the top case dissassembled, the connector with the black patch on the top is likely loose. Clean the connections thoroughly with alcohol and a Q-Tip and reassemble. If it doesn't work, or only works partially, another cleaning may help (I had to go in twice).http://www.celtnet.org.uk/mobile-phone/disassemble-motorola-v3-3.php