Library disappeared

I am freaking out because I seem to have lost a library of 1000s of annotated references - years of work… I opened a NEW library and imported about 270 references from an .ris file. Now my entire old library seems to have disappeared and in my old library , all that shows is these new 270 references. Any ideas on how I can retrieve all my years of work? (And I need that old library - use it constantly for my work). THanks.

Can you take a screen shot of the library  display and attach it (Attachments/choose file at the bottom of a reply window).  If you are on an Windows 7 machine, there is a “snipping tool” you can use and save as a .jpg