I run Ubuntu 18.04 dual-boot with Windows XP. I recently was trying to recover a sad USB drive using "Disks" and accidentally hit delete and wiped the partition containing Grub and whatever else needed to boot my PC.
I have been running this PC by starting from my ext HDD which gives me the option to start Ubuntu or Windows.
I would like to reinstall the files needed to start my PC without deleting all the other files on the Ext HDD.
I have taken a snapshot of the HDD shown by TestDisk and one Shown by G-parted if that is of any help in finding a solution. I will be deeply grateful for any help at all please.

Attached Files

ScreenShot-USB-HDD.pdf (370.5 KB, 49 views)

It is very difficult to view the images you posted but from what I can see, you have Linux (Ubuntu) on sdb. Where is XP, on another drive? Is this an EFI install of Ubuntu? There is not EFI partition and I'm not sure that XP can be installed and/or boot from a GPT or EFI install. As far as reinstalling Grub, the Ubuntu site at the link below gives a number of methods to use in different situations.

https://help.ubuntu.com/community/Grub2/Installing

Thank you Yancek I shall read those notes but meantime I repost the images. Maybe you can see something else missing. I think I accidentally deleted the partition also??

Attached Files

ScreenShot-USB-HDD.pdf (327.0 KB, 38 views)

The image in your second post shows you have 2 500GB hard drives. The GParted shows 41GB unallocated space after the first partition. Is this where the partition was that you deleted? Is your old xp on the other drive? Did you have a separate boot partition for Ubuntu in this space? Seems unlikely there would be a 40GB boot partition. Is this the drive on which you have Ubuntu as there only Linux partitions there? Is this a Legacy install where you have Grub boot code in the MBR? If so, on which drive do you usually boot from?

Thanks for the quick reply and Merry Christmas to you and yours.
I shall work my way through your questions and get back to you soon.