Is there a way to sign without having to print it all out and mail it in. I have no way of printing the paperwork

Only a small fraction of tax returns need to be mailed.  What did the program tell for the reason your tax return cannot be e-filed?

If you e-file a return, you do not physically "sign" it.   Your signature is electronic when you enter your 2019 AGI to identify yourself to the IRS as the same person who used that SSN for a 2019 return.  You can only e-file a 2020 return.  No other years can be e-filed.

If you want to print your return to mail in, you have to figure out your own printer problems.

I DO NOT HAVE A PRINTER—WHAT CAN I DO?

We cannot solve your printer problem for you  If you do not have a working printer, you can access your account from any computer that has internet access and print your return.  So perhaps you need to see if a friend or relative can let you print from a computer with a printer.  Or print it at a UPS place or Staples, etc.