iPhone one row is not working

In my iPhone 4 789 keys are not working if i press 7,8,9 key their top key 4,5,6 or bottom key *,0,# is displaying. the entire row is not working.if the scratched grad is present on the screen when these problem occur, if u remove the scratched grad the problem is solved,if there is no scratched grad when these problem occur i need to use the scratched grad to resolve these problem.After removing or using the scratched grad the screen will work fine for 1 week to 10 days then again the problem will appear back . example if i touch any option on that particular row up or below option is selecting. please provide the permanent solution. let me know whether it is lcd problem or any other.