I have a serious problem in registry editer. Whwn I run it I am able to run it but can't change anything in regedit. Evan I can't click any of option in that window. In addition to this when I try to close regedit I can't close it. I have to close it only by task manager. 1 more thing. I have used "regisrty mechanics" & "windows registry repair" software to fix registry. I think this problem may occur by running this software. Please give me solution. I will be thankful to you.

Why are you manually editing the registry in the first place ?
This is an incredibaly dangerous thing to do, especially for some one that 110% sure of what they are doing.
Delete or change the wrong key and your system will NOT restart.