How do I access my lost files??

Guys help so I've been tryna download my fking douyin back in my phone but it won't for some reason cuz it's said that the file already existed?? So basically my phone restarted last month and I've been tryna redownload some of my apps some does still work but apps like douyin and proccd won't download cuz the file already existed but I keep searching for it in my file manager and there's nothing