Dual boot ubuntu windows 10 - only boots into ubuntu - no boot selection menu

[yinnxbutu]

I ran boot-repair and it seemed to be working. At least it thinks it worked but when I rebooted it still does the same thing, boots straight to Ubuntu. So, if you think of anything else please let me know. I really appreciate your help!

[tea for one]

Back to square one - but, never mind, let's see..........
From your comment, I deduce that the Grub menu does not appear when you power on the PC.
Is that correct?

Power on from cold and tap the left shift key (say, every half second), any sign of Grub?

[yinnxbutu]

Yes, a grub menu came up that time, but there's no windows selection. It says hit "e" to edit, and then it shows a bunch of stuff. Then I backed out. I'll try to attach some pics from the screen.

[oldfred]

To dual boot both systems if on one drive must be in same boot mode, or both BIOS or both UEFI.

Windows has to have MBR(msdos) partitioning for old BIOS/Legacy/CSM boot.
Windows has to have newer gpt partitioning for UEFI boot. Microsoft has required UEFI/gpt installs by vendors since release of Windows 8 in 2012. So all newer hardware is UEFI.
Windows 7 originally was BIOS only but later releases included UEFI/gpt boot, but only with UEFI Secure Boot off.
Note conversion from MBR to gpt totally erases a drive. So backups required.

Ubuntu allows UEFI install to MBR drives, but probably should not as it creates the problem you now have.
You can only have one boot flag per drive. UEFI has ESP that must have boot flag. Windows in BIOS mode must have boot flag on its boot partition or which every partition has boot files, your sda1. Often boot partition is a smaller NTFS partition before the "Crive" partition.
UEFI & BIOS write hardware data to drive totally differently, so once you start booting you cannot switch. Or grub can only boot other installs in same boot mode.

You need to always have a Windows repair recovery flash drive & Ubuntu live installer to make repairs.
Grub can only boot working Windows, so then you have to temporarily install Windows boot loader, fix Windows and then restore grub. Boot-Repair actually can install a Windows type boot loader (syslinux) to MBR to directly boot Windows.

[yancek]

If the link to boot repair in your initial post is current, the problem is that you have/had both windows and Ubuntu installed in Legacy mode. From boot repair, line 5 shows: Grub2 (v2.00) is installed in the MBR of /dev/sda AND line 47 shows sda5 is an EFI partition with only ubuntu boot files. Line 91 in boot repair shows the drive is not gpt therefore windows can't boot EFI even if it had EFI boot files which it does not. Do you have Legacy/CSM boot enabled in the BIOS/

Just saw the post by oldfred above. Make the suggested changes.

[tea for one]

Now that boot-repair has re-installed Grub, can you return to post 4 and see if your /etc/default/grub config includes the OS-Prober
If not, make the changes and update-grub.

[yinnxbutu]

I did the /etc/default/grub and OS-Prober line is still there. Ran update-grub but nothing has changed.
So I ran boot-repair again and let it do it's recommended repair. But still no luck.
Then I booted into my Windows flash drive and clicked to troubleshoot startup problems and it said was not able to repair startup.

I'm wondering if there is easy way to just uninstall Ubuntu so as to be left with just windows. Then, if still cannot boot into Windows maybe I can reinstall Windows and start again there. (?)

[yancek]

I'm wondering if there is easy way to just uninstall Ubuntu so as to be left with just windows

There is no point in doing that. If you want to remove Ubuntu and just have windows you would just go into windows and use Disk Management to format the partition(s) on which you have Ubuntu to an ntfs filesystem. Since you can't boot windows you would need some windows recovery disk/usb.

You never indicated if you enabled Legacy/CSM boot in your BIOS. You can see that both windows and Ubuntu are Legacy installs so enable Legacy/CSM in the BIOS. Your efi partition isn't much use for a dual boot since it only has Ubuntu files in it.

When you ran boot repair the last time, did you boot in UEFI mode or Legacy mode? Should be Legacy mode.

[tea for one]

Which Windows iso do you have?
Does it boot in Legacy mode?
Have you backed up your personal data from both Windows and Ubuntu?

[yinnxbutu]

When you ran boot repair the last time, did you boot in UEFI mode or Legacy mode? Should be Legacy mode.

Yes it is Legacy