I am guessing that you are on the Mendix Studio Pro. In that case, if you want to see the changes you have made, simply go to the Changes tab. If the changes displayed are not specific enough, click on one of the changes and you will see a detailed information of which elements were changed, moved, deleted, etc.
If you don’t really know where it all went wrong, you can revert all the changes back into the previous version, either by right-clicking on the page/microflow that contains the changes then “Revert change”, or do it globally by clicking Version Control → Revert All Changes.
Once you get rid of the error, commit it to Team Server so you can pull the fixed version again from the Mendix Studio.
Best of luck!
Select View → Changes to see the change made since you last downloaded the app from TeamServer, Depending on the version your using, you’ll get detailed information by double-clicking on each changed object, and this should help indicate what you have deleted.
Once you have fixed the problem, select Version Control → Commit to save the changes back to TeamServer and for Studio users to see the changes.