got stuck

avrdude: stk500_getsync(): not in sync: resp=0x00

my board was working in very good condition for last 4 months but now iam getting this error whenever i upload any program to the board..
pls give me some clues ,ideas to solve it..

There are plenty off Topics to read, when you search for avrdude and sync.
For me, it was the upgrade to IDE 1.0.5 that solved my sync Problems.