My Facebook Account Hacked, Lost Two-Factor Authentication

My mobile device and desktop computer both became infected with a virus, and someone hacked into my Facebook account. I had no choice but to format both of my devices and during the process, the app I use for two-factor authentication was accidentally removed. Because it requires a code for two-factor authentication, which I cannot generate without the app, I am currently unable to reset my Facebook password or log in because of this requirement. My email address and phone number are both linked to the account, but I can't seem to find the associated app. Please, I've been unable to access my account for the past few months; I require assistance.