Manual transmission won't shift into any gear except when engine off. What's up?

replace the clutch. by driving it the way it is, you may have damaged the trans but only a shop can verify that. Roy

Take it to a shop and get a compression test, I think you will find that there still lots of life in the car. And take it easy on the new clutch: They do wear out if they are slipped a lot or driven harder than a family car. Who new.