Since last two weeks my left hand finger is not able to straighten as before. There is no swelling.?

Question

What may be the reason?

Answer 1

A broken tendon will cause this problem. If this is your problem you need to go to a doctor that specializes in hands and get a small cast for your finger.

Answer 2

It sounds as if the finger (or a joint therein) may be dislocated.  Unfortunately, the only way to set the finger is to pop it back into joint, which is quite painful.  If so, then either you or a doctor can do it.  I hope this helps a bit.  Best of luck to you.