Timeline says no sequence

For the past couple months I have been marking videos and adding them to the timeline so I can move onto the assembly stage. I have been saving them and reopening many times and everything is all in tact. Today I opened my project and all the uploaded raw footage was there, including one's I have recently uploaded by all if my selected and modified clips that I have brought over to the timeline are gone and it says no sequence. I never leave Premier Pro without saving, and even if I did it should have the sequence that I have been building on for months. I have searched the internet front to back and no answers seem to pertain to my situation. Pleaser help!