Your best bet is to backup everything using the system imaging technique. The reason for this is that if you reinstall the OS, and then try to restore the backed-up applications, things will not work very well since the newly installed OS registry entries have no knowledge of the previously installed applications. I hope that makes sense.
If you use the system imaging technique, you create an image of the entire system : OS, registry and applications. If you choose to restore the image, then you bring everything back across onto the PC in perfect working order - importantly, the registry still correctly informs the OS about the applications in a way that everything still works.
There are many programs to use for imaging, but my own personal preference is for Macrium Reflect FREE
Currently, it sounds that since you already want to do a reinstallation, the only choice is to reinstall the applications. Depending on the state of the corruption, you might attmept a sfc /scannow
command from the command prompt. See this tutorial below, to try that: SFC /SCANNOW Command - System File Checker