This problem happened because either u install new version of jdk so you have both 32bit version and 64bit
how to solve the problem is just go open computer & go to c then you will see
after that you probably use 32 bit so just chose C:\Program Files
and there you will find folder called java
in it

so you have many different version of jdk so easily chose jre7
and to to bin and you will find javaw.exe in it like

now only just take that path copy and go to start type eclipse.ini you will see text file just open it and before -vmargs
write -vm enter path like photo

now just open eclipse again and have fun :D