Turn on a multi-functional pressure cooker (such as Instant Pot®) and select Saute function. Add ground beef, mushrooms, onions, and garlic. Cook and stir until beef is browned and crumbly and onions are soft, 5 to 7 minutes. Add water, soup, noodles, Worcestershire, and dry soup mix. Close and lock the lid.
Select high pressure according to manufacturer’s instructions; set timer for 3 minutes. Allow 10 to 15 minutes for pressure to build.
Release pressure using the natural-release method according to manufacturer’s instructions, 10 to 40 minutes. Unlock and remove the lid. Stir in sour cream.