Can we restore backup in quickbooks online ?

Good to have you here, annamalai-integr.

I can share some info about restoring your backup in QuickBooks Online.

Restoring backup in QuickBooks Online Simple Start, Essentials, and Plus versions is currently unavailable. You can only backup and restore your data via a spreadsheet including but not limited to the following:

• Customer
• Suppliers
• Products and services
• Invoices
• Bills

However, if you the Online Backup and Restore app, you can restore your latest backup data from a specific time and date. You can go through this article for more details: Back up and restore your QuickBooks Online Advanced company (formerly ChronoBooks). 

You might want to check out this article about the types and supported format when you restore data: Common questions about importing data to QuickBooks Online.

You can post any additional questions about restoring backup in QuickBooks here or if you have other concerns aside from this topic, please let me know. Take care!

@annamalai-integr 

What kind of backup file do you have? Are you using a backup restore app or else?

https://rewindio.grsm.io/quickbooks