Forgot password and GRUB not working

I forgot user password in ubuntu 19.04. I tried to change through GRUB, but it’s not loading. On clicking and holding the shift key… GRUB loading pops on screen for few seconds and then nothing happens.

After many and many attempts it’s Still the same. I don’t want to lose my data. I should I do next.

Please help.

If your /home directory is not encrypted, you can access the data from a live medium.

How can I access the data from a live medium