Decrap is a rather dangerous tool for beginners, because it fully removes all the installed software and all the non-standard Start menu and Desktop icons.
So, only use this feature if you know what you are doing!
In fully automatic mode the program will automatically and without any further confirmations uninstall all the third party software from your computer and after this the Windows registry is also cleaned. This option always creates a System Restore Point. Only use this option if you know what you are doing!
If you don't check the fully automatic mode, during the process you have also the possibility to let the program create a System Restore Point.
What mode did you use: fully automatic or not? Did you let the program create a System Restore Point? If so, run the System Restore.
If not, maybe you have a recent System Restore Point automatically created by Windows at a time before running the Decrap tool. Check that and if you have a recent System Restore Point, run System Restore.
But it's possible some of your uninstalled software must be reinstalled.