Why can't you use the stock music app?
I use iZip Pro for playing music sometimes. Another is Documents by Readdle. I think both play offline, if they're downloaded offline in the stock music app. If you want something fancy, TunesFlow is nice.
Why did you start 2 threads on this?
You can download videos from Twitter with this app. I just checked to be sure. It's tricky though.
Video Saver Pro - Video Player for Cloud Platform by Nguyen T Nam Giang
If you deleted your photos from your device, then they would no longer be in iCloud if a back up was done after the deletion. If you remember the email address used for your Apple ID, you can reset the password.
I use SwiftKey as my default keyboard. I use the predictive word method, rather than swipe. Swipe never worked well for my fat fingers. But many do like it. I like the ability to delete words or non words from the SwiftKey keyboard dictionary. I have no idea which keyboard is the fastest...