Not able to setup my personal hotspot even though I had used in past

Use these steps first

Restart the iPhone or iPad that provides Personal Hotspot and the other device that needs to connect to Personal Hotspot. Make sure that you have the latest version of iOS. On the iPhone or iPad that provides Personal Hotspot, go to Settings > General > Reset, then tap Reset Network Settings.

If Personal Hotspot is not working on your iPhone or iPad (Wi-Fi

The Hotspot is a carrier-specific feature. Contact your carrier, if it is not appearing on your device.

Also, check the following

1. Network coverage and stability
2. Data Balance
3. On your windows (See if WiFi Auto Joins is enabled)
4. Also, check if you have any stronger WiFi signal around your computer.

The link on top of this page, under the "Related Article” is the method. If that link did not help then please mention the exact difficulty faced by you.