Can I fire up my turbo tax from last year (2019) and return to TT 2020

I had installed and just about completed my 2020 returns.  I reopened the 2019 TT software and was playing around in there. Now I cannot get into TT 2020? It says it wants to install updates as usual, takes a few minutes then errors out.  No matter what I do I can no longer access TT2020...why would this happen?