I am trying to file another return and it says account is running switch users. I can't get turbo tax to open

All you have to do is go to far left upper corner and hit 'File' and 'Start New Return.'   

Oh are you trying to start the program again?  No you just stay in the same program.  Go up to File-New.  Be sure to first save your return by going to File-Save.  

And be sure to save each return with a different name.  If your dad has the same first name as you his return might overwrite yours.  So when you save his return the first time go to File-Save As.  And be sure to save frequently.  

Your tax files end in .tax2018 and are saved in your Documents in the Turbo Tax folder.

I have the same problem only I am trying to open 2018 which I was just in and then closed and tryed to go back and open again and am getting the same error code 70001.