Please assist? Original OS Windows 10. 2nd OS Ubuntu 18.04.1. Both installed on a separate SSD from storage/documents HDD.

Worked perfectly until a week ago, but upon waking I could no longer boot to Windows, only Ubuntu. So apparently something is wrong with GRUB2, but I've no idea what. Please speak as if I know nothing (mostly true re boot repair, OS problems)

Thank much!

marked as duplicate by Kulfy, user535733, karel, Kristopher Ives, Eric Carvalho May 20 at 22:57

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  • If you still can select Windows from Grub then there's nothing wrong with Grub. If Windows doesn't boot or gives an error that's a Windows problem. – GabrielaGarcia May 18 at 23:04
  • Grub only boots working Windows. Often you can still boot Windows directly from UEFI boot menu & one time boot key like f10 or f12. If Windows updates turned fast start up on, or Windows needs chkdsk those prevent grub from booting it. So fix Windows with Windows repair disk or if you can boot Windows directly and get into repair console fix the Windows issue. Then grub should boot it again. – oldfred May 19 at 2:39

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