My wife and I seperated January 3rd 2020. We are no contact and she filed our taxes last year. I don't even know what web site she used to file. What do I do?

This is really a legal question, not so much of a tax question. Your attorneys should be helping you with this.

Since you are still legally married on December 31, you could file as married filing jointly. This usually will result in lower overall taxes or a larger refund, but you would want to decide in advance how to divide the refund and make sure that all of the attorneys involved in the situation knew what was going on and approved.

If you don’t want to or can’t file jointly, then your other option is to file as married filing separately.  For this, you prepare a tax return in your own name that only lists your income and deductions. The only information you need for your spouse is their name and Social Security number. To e-file, you would also need your pin or adjusted gross income from last year. If you don’t know that and can’t get it, you can file by mail..