Microsoft SQL service compact 4.0 ENU

You should ask advise before blindley uninstalling stuff. Do you have any database apps on your system?

System Restore takes a snapshot of your Windows apps, system files and drivers from that moment in time and saves it in a Restore Point. You can manually create a restore point or sometimes installing software will create a restore point automatically for you. If you have uninstalled an app accidentally, or decided you didn't want to uninstall it, System Restore may be able to restore it from a restore point. System Restore does not save or store any applications. Once an app is uninstalled it is gone. Once in a while an app can be restored using System Restore, but you shouldn't count on it. User files (ie) Documents, Pictures etc that are deleted and removed from the Recycle Bin cannot be restored

Do you have a Database that you use for yourself or small business? If so, without this app, you may not be able to access the database.

Microsoft SQL Server Compact 4.0 ENU, commonly referred to as SQL Server Compact, is a lightweight, in-process database engine developed by Microsoft. It is designed for applications that require a local database storage but do not need the full functionality and scalability of a larger database server like SQL Server.

Murf1954 said:

what is it? i just uninstalled it on google it said has something to do with mobile . Now that i uninsteed it will my computer fail to work?

It was likely installed with some other program which requires it.
uninstalling it is similar as uninstalling VC++ redist, program which require it might not function properly.