Oh that sounds like no fun at all. 
You shouldn’t have an issue using your project file again. You will just need to make sure to backup your project folder in a location you can still access. When you install the same version engine or a later version you can simply open the engine. If the engine version that it was developed with is not installed, you will see a window pop up that looks like this:
It will contain a drop down for all the current versions of the engine that are installed.
Once you’re back up and running if you’re still having the issue feel free to post back here and it’ll re-open the questions and we can investigate from there or if you have other questions with this topic that’s fine too.