What is a good alternative to "I was screwed"? [duplicate]

Solution 1:

First of all, it should be you're, not your.

You can use this more formal phrase: "You're doomed."

Solution 2:

Fix your "your/you are" mistake and do not use contractions in formal writing.

The answer to your question depends on how strong your statement needs to be. You could use a mild version You are in trouble, or possibly you are out of options now. The already suggested you are doomed is a bit more dramatic. As a threat, it could be replaced by you are finished.