Hopefully it is in your filing cabinet because that's where it should be. Every consumer should make certain they get a copy of their HUD-1 at closing. Depending on some other party to maintain a copy and provide a back up when you need it is risky.
Okay, so maybe you lost your copy or you never got one, what do you do now? Call everybody else in the transaction. Hope they are still in business, that they have a copy and are willing to share it with you. Start with your title agent, then your real estate agent and finally your mortgage lender. If you strike out there, you could try the seller or the seller's attorney.
If you are one of my customers, I will ask for a written request and upon receipt, I will e-mail or fax the HUD-1 to you within one business day.