I filled my boyfriends taxes for him and after I finished I realized he gave me the W'2 from last year in other documents I needed. How do I fix it

If you actually submitted and filed with the wrong year info (or you were trying to file a 2018 return) or left something out etc., then you have to wait until the IRS starts taking returns on Jan 27 and see if it is Accepted or Rejected. If it Rejects you can fix it or add the missing info and resend it. BUT if it is Accepted then you need to wait for the IRS to fully process your return and you get the first refund or pay the tax due. Then you can fill out an Amended Return 1040X. So if you have filed DO NOT change or enter anything else into your return until you find out if you have to amend.

Again DO NOT CHANGE or enter anything into your return if you already filed. You will have to start the Amended return with the original return that was filed. How to amend 2019
https://ttlc.intuit.com/community/amending/help/how-do-i-amend-my-turbotax-online-return/00/27577