I used to be good at math and calculus and statistics, but not anymore. But I can still try to help. I hope other people with more tax experience can chime in here, too.

Hang in there. Math bothers a lot of people, so you're not alone in that struggle. And if you do have an undiagnosed learning disability in this area, it's okay. Many people do. As long as it's not a requirement for your job (and only these confusing tax forms), then you're good!

You can request your old taxes from your former employers. You just contact their human resources departments and ask them for a copy of your tax forms for the year(s) you worked for them. They should be able to get you those via snail mail. That might take time for you to receive, due to delays in mailing. If your employer is okay with that, then wait for your old taxes to arrive.

Do you need to know your past tax info to complete the W-4? It's been a while, so I forgot. If you don't or if you can estimate, then we can work from there.

Is there a due date when your boss expects all this done?