It is highly recommended that you back up the Oracle home before any patch operation. You can back up the Oracle home using your preferred method.
You can use any method such as zip, cp -r, tar, and cpio to compress the Oracle home.
If the Oracle home does not appear when you execute the opatch lsinventory -detail command, the Oracle home might be missing from the Central Inventory, or the Central Inventory itself could be missing or corrupted.
If the Oracle home is listed when you execute the opatch lsinventory -detail command, but the products and components within the Oracle home are not listed, the inventory within the Oracle home (local inventory) might be missing or corrupted.
If the local inventory is corrupted or lost for some reason, you must restore the entire Oracle home if it was backed up. If a backup does not exist, you may have to reinstall the software.