It's not worth the time to try to save the carpet. Remove the carpet, the musty/mildew smell is caused by mold, take a garden sprayer and mix one cup of chlorine with two gallons of water, and spray the ceiling walls and floors making sure you really cover every area to kill the mold, then you need to run fans on the floors and ceiling for two to four days on average to dry the bassment out. that is the safest way to know no one will get sick from mold in your family.

You are required by law to file if your income level is above the federal / stae guidelines.

You might not owe any additional tax but have a refund due. The only way to get the refund is to file. They do't send it to you automatically.

If you are due a refund you must file within 3 years of the due date (or extended due date) to get it. If longer than that your refund just goes to service the public debt.