Welcome to Android Central! Which social media platform? Are you unable to log into that account on the web from your computer? I'm not aware of any social media platform that is limited to an app on your phone, and not also accessible on your computer browser.
As far as recovering anything from a dead phone, you can't. If it's just a totally dead battery, replacing the battery would allow you to get into the phone and run an app like Apk Extractor (or App Backup & Restore if you want to recover a lot of apps), to recover the installation file for the apps. And the data itself is normally kept on the server on social media sites.
But just installing the app from Play should allow you to log into your account (you'll need to remember your login [or the email address you used] and password, of course). It doesn't have to be the old app itself - any new installation of the app, or a web browser, as B. Diddy said, should work.