Hi marymithun,
Welcome to the Apple Community.
Apple support has articles online to help:
If you wish, you can follow the guidance, step by step.
Back up and restore your iPhone or iPad to your Mac or to iCloud
says:
In the Finder  on your Mac, select the device in the Finder sidebar.
If you connect your device to your Mac using a USB cable and don’t see the device in the Finder sidebar,
see If your device doesn’t appear in the sidebar.Â
Complete article: https://support.apple.com/en-au/guide/mac-help/mchla3c8ed03/mac
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OR
If you use a PC
Restore your iPhone, iPad or iPod touch in iTunes on PC
https://support.apple.com/en-au/guide/itunes/itnsdb1fe305/windows
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Hope this helps :-)