Originally, my Ubuntu partition was ~600 GB and after resizing it to ~182 it worked fine for an evening but now I am no longer able to boot into it.
The boot screen automatically takes me to the Windows install instead of the ubuntu screen with ubuntu as the primary option & a 5 second delay before automatically continuing to boot into ubuntu. I'm not knowledgeable on partitioning as far as what the boot process looks like, what needs to be together, etc... I think a boot partition may have been removed sommehow? I remember two very small partitions and now there is only one.
In this picture, from left to right are what I think is 512 MB for the windows boot partition, 180 GB for windows, 180 GB for Ubuntu, 142 GB unallocated, 400 GB for storage/access from both OS's, and 15.9 GB that I also don't know what it does, but I think it's the Linux swap.
I think when I resized / moved things I may have separated my Ubuntu partition from something important? That or after resizing I somehow deleted an important partition for booting into Ubuntu... would appreciate any help! I already did some googling and reading, but didn't find any solid answers... I likely will boot into Ubuntu with a USB and use GParted to also try to view what's going on, and maybe just reinstall Ubuntu...?
Edit after using Boot-repair:
Currently, my ability to boot into Ubuntu and Windows has been fixed, though there are many more options for booting into Windows in the GRUB screen, and only one of them really works... the pastebin is here http://paste.ubuntu.com/p/4YygHynjrc/