I picked up my phone and saw that the home button is not working. Then I turned it off and on again and it started working. But after a few minutes, both buttons stopped working. What can I do now ?
Wipe cache partition if you can get the buttons to cooperate.
If the dial screen is available, dial *#0*# to get you into service screen where you can test hardware.
If it fails, take it to Samsung shop to get fixed.