You are posting your question to someone else's thread that was about a Business return that was prepared using desktop software that can only be used on a Windows computer. We do not know what you prepared or what software you used, since you have not said.
If you, in fact, used desktop software:
If you used desktop software downloaded/installed from a CD to your own computer, then the tax files are stored locally on your own hard drive or any backup device you used like a flash drive. They are not stored online. If you cannot recover them due to a hard drive failure, etc. you can get a free transcript from the IRS or for a fee of $50, an actual copy of the return.
Contact your state for copies of previous state returns.