I signed a personal guarantee loan with a local bank for $100000.00 a few years ago. Then I left the partnership 1 1/2 years later, and the remaining two partners stayed and continued the business. Then they filed bankruptcy the following year, and now last week I was served with a summons. I only have 21 days to file a response with the court, and I can't afford an attorney. What form do I need to file with the court for my response?

For that amount of money I'd get an attorney. You can file a notice of Intent to Defend. I doubt if it needs to be on a specific form. But I don't see where you have any defense. You signed a personal guarantee. Therefore you owe the money.