My former employer filed bankrupcty and I don't know if he was paying the iRS taxes that he withheld from my checks. Will I have to pay the IRS that money if he didn't? And if so what can I do to still receive a tax return?

What does the W2 state that they gave you

If the W-2 shows that the taxes were paid, you can safely assume that they were paid.

If they were not, the IRS will NOT come to you for the money. They will go to the employer.