Windows 7 Dual Boot Windows 7 & Linux boot issues

[SavorySilicon]

Hello, I have some experience setting up Windows Linux Dual boot, but unfortunately yesterday I ran into a problem. The grub menu does not have Windows 7 on it, and I don't know how to get it on there. I installed a new version of Linux onto an old laptop. The laptop does not have UEFI, it has the old BIOS system only, and I think the grub menu installation expected the Windows to have an entry in an ESP partition maybe. I don't know. There was no ESP partition prior to installing Linux ElementaryOS (an ubuntu variant)

This is for a client, and his applications on the Windows partition are important for his business, he cannot lose them, so we cannot merely reinstall Windows 7 and clear the system. How do I get Windows 7 on the Grub menu, or just go back to booting directly into Windows 7?

Lenovo laptop, very old, Windows 7 OEM 64-bit
4Gb RAM Intel i3 2gz

I have already attempted to use:
Boot-Recovery Live CD (new and old versions)
Grub-Recovery (the version I had was UEFI boot only, if you have the link to the BIOS version please reply with it)
Boot Ice (don't know the exact steps to take)
Windows 10 automated Startup Repair

Thank you Windows Forum for all your help!

 

[Neemobeer]

Have you run sudo grub-update?

 

[SavorySilicon]

Have you run sudo grub-update?

I have used the graphical Grub-Customizer, it does the os-prober, but it does not find the Windows C: partition. I have tried manually creating a Grub2 boot entry for each Windows-related partition, but when I restart and boot from these new menu entries, it does not work, and displays an error, saying the thing it is looking for is not there.

 

[Neemobeer]

I'd say there are problems with the partitions then. You'll likely need to boot to a Windows recovery disc/usb and use bootrec to fix the partitions. Afterward Linux will break and you would need to boot to a live Linux disc/usb and remount the filesystem on your distro RW and then use chroot to switch to it and re-run grub-update.

 

[SavorySilicon]

Thank you for those suggestions Neemobeer. What do you mean problems with the partitions? What sort of problems? Why doesn't Grub see them? They are right there. What are all of the steps to do with bootrec? I assume you mean to go to the Windows 10 Recovery command line, but after that, I don't know what the steps are. We are not worried about losing the Linux, that was just an experiment for the client. What are all of the steps, and what possible problems could happen? Thank you so much Neemobeer, you are very helpful. Don't forget this is a BIOS 64-bit system, not a UEFI.

 

[Neemobeer]

I mean there is likely something wrong with the Windows partitions such that Linux can't see it. Did you try running os-prober and see if it returns any errors?

 

[SavorySilicon]

Yes I already tried all the basic stuff before posting this. os-prober and sudo grub-update. I resolved the issue by myself. I believe the core issue was that I was attempting to install the new mbr too far from the beginning of the disk.

 

[Neemobeer]

The MBR is always the first sector.