This happened for a short bit on my laptop as well, running Windows 10. I'm actually about to install Ubuntu and run Litecoin Core binaries soon.
Anyway, in response to your question - If you view the process in your task manager, try expanding the process, then right clicking the process, and selecting Maximize.
For some reason, Windows decided to keep the process running in the back ground. Using process above might help to bring the window back to the forefront.
Also, be sure to always keep a backup your wallet.dat file before you decide to do any re-installation.