Iphone 3gs Restarting ..

[max414]

I have an Iphone 3gs that just keeps on restarting
It powers on , goes to apple logo and restarts ..
.and keeps doing it until I press and hold power and home buttons for a few seconds and then phone shuts off

I tried to put it in recovery mood
by holding home button (when its off ) and connecting to pc(itunes)
but fails and keep doing the restart loop

I tried to put in dfu
but i cant ..some instruction on it considering that my phone keeps restarting ..

[AustinHarleyD]

Try DFU again and then restore it in iTunes.

[max414]

Try DFU again and then restore it in iTunes.

Sir i have been trying that for a while now , I am not able to do it
Thats why posted here to get some help

Phone connected to itunes , keeps restarting
1.I press and hold the power n sleep button for 10 seconds
2.phone shutts of
3.I keep holding the sleep button ,but the iphone still boots normal i.e apple logo shows up and restarts again