Re: Error: no such partition. Plus no USB..
If you already had the maximum of three primary and one extended partition, when you created another from inside Win7, you most likely converted your partitions to Dynamic Disks -- which Ubuntu can't see or use. That would explain the inability for it to boot now.
To check this, boot into Win7 and look at the partitions (MS calls them "drives") in the Disk Management tool and tell us what is there.
Ubuntu 16.04 Mate, Mint 18 Mate; MS Win 8.1, MS Win10 Pro.
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