Problem in Edit Mode

Hi there. I have been using Blender for about a month now and have never come across this problem before. I accidentaly pressed some button and now some of the mesh is stuck in object mode and the other half is in edit mode. How do I fix this because I really don’t want to start all over again, this took a long time. Thanks, Urashima

I guess you split them by accident

Goto object mode - select both objects (shift and right click) then control J to join them back up

For future reference, you must have pressed P-key with some mesh selected.