I have used clean my mac and after that some of my icons from launch pad have disappeared, mail is opening but not displaying the emails, app store is not opening...what should i do? I request for urgent help ...please...??

Mac's do a pretty good job of keeping themselves tidy and not clogging up with masses of redundant files, so the use of cleanup utilities tends to be unecessary - - - and can cause more problems than it solves!

The apps that no longer appear in Launchpad - are they still in your Applications folder accessed through Finder? If so, try launching them from there and see if they reappear in Launchpad.

As for non-displayed emails, Clean My Mac may have wiped them. But try this - back up any important files, then select a folder in Mail (say, inbox), click Mailbox in top menu, then click rebuild (the last option on that menu). If they do not reappear, then you could try accessing them from your mail/internet provider providing you have opted to keep messages on server.

As a last resort, you could try restore from Time Machine - you do keep a backup don't you?