Go to your cPanel. Check the php.ini file as well (max_execution_time, etc. ).
You should first convert your theme or backup file into a .zip, then upload it to cPanel and extract it.
Go to the Dashboard, then restore it from the backup.
Also, use this Plugin ---- https://drive.google.com/file/d/14ZJYO1O4ixJoWINf1B4KbfLU_jSocVoW/view?usp=sharing
This is the best modified plugin.