Hello, I live overseas and I haven't filed yet. I would like to know how do I file without a W2? Also is there any other forms I need to complete to file? Thanks.

If you are a US citizen, you can file a tax return if you have income.  The income does not have to be in the form of a W-2.  Use this link to start a US tax return.  Start a Form 1040 - US Tax Return

If you are not a citizen or resident of the US but have US income to report, you can use Sprintax to file your nonresident tax return (1040NR).