the other project is not lost - but can be fiddely to find the (most of the time) ONE asset which brings your Editor to crash. check the logs in the “Saved\Logs” subfolder of your project if it says something meaningful or upload your log here.
if not, I would suggest following steps:
- duplicate your project folder as a backup
- delete saved, intermediate, build folders (mostly all except Config/Content/Source/)
- try to load your project - if it works good
if not continue - open your .uproject file and remove the plugins and modules you may have setup, check if it loads, if not
- go to content folder, search for all files in (sub-)folders, eg: in windows explorer search bar enter a dot (".") which will give you all files
- order by modified date and start deleting the ones, recently modified (remember - step 1
) - try to load your project
- if it doesn’t work, goto step 6