I have a macbook Pro, I reset it, and also removed my backup OS, how can I then reinstall my MacBook Pro

Hi,

Try to start up in Recovery Mode and reformat your boot drive then reinstall macOS.

Use macOS Recovery on an Intel-based Mac - Apple Support

Use macOS Recovery on a Mac with Apple silicon - Apple Support

If it doesn't help, take your MacBook Pro to your local retail AppleStore, Genius Bar or Apple Authorized Service Provider to install macOS on your MacBook Pro there.

Genius Bar Reservation and Apple Support Options - Apple

Find Locations - Apple

As far as I know, it's free.

For Intel Macs after 2010, I like this article:

How to reinstall macOS - Apple Support

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what model-year MacBook Pro?