Don't worry. You have 3 years to do the amendment, so there is no rush to do it today, although you do want to do it before 04/15/19 in case you owe taxes on it. Take your time and locate the W-2 so that you do the amendment correctly. You surely don't want to have to amend your amendment. If you can't locate it, contact the employer and let them know you need a copy. If you are anything like me, you won't find it until you stop looking for it.
