Have to amend tax due to new 1099-k. when amending does the w2, which did not change, have to be sent in with the forms?

Unless there is a change on your W2 or new W2, you don't have to mail it with your amended return.

You only have to attach the new information(1099-K).

See this TurboTax support FAQ for amending a tax return - https://ttlc.intuit.com/questions/1894381-how-to-amend-change-or-correct-a-return-you-already-filed