Hello I am Olivia Munn. Troubleshooting QuickBooks file extension issues requires systematic steps. Firstly, ensure you're using a compatible version of QuickBooks. Attempt to open the file with the correct program. If it doesn't work, try opening it on a different computer. Renaming the file extension to a recognized format might also help. Utilize QuickBooks' built-in repair tools or third-party software if necessary. Restoring from a backup is a viable option as well. Consulting QuickBooks support or community forums can provide further insight.