Hello.. can u please help me after my phone will back up some of my important photos are missing can u please help me then how?

Backing up does not alter any of the data on your phone.

What did you actually do?

If you restored from a backup, that completely erases the device and imports the data from the backup you’re restoring from.

So you restored it from a backup. Anything that wasn’t backed up before you did that is gone. There is no getting it back.