Yeah as Sarah said- the answer is the obvious... Quit smoking weed!
weed affects people differently, it is not as safe as people assume. It can have adverse mental side affects, and the brain is a very powerful thing indeed. It can fabricate sensations, or in your cause, the lack of them from nowhere. You are probably getting paranoid due to smoking weed, so maybe you should stay away from it all together. If you do and a month down the line you still have no feeling in your fingers, go and see a doctor..
Quit smoking weed and this will go away.