[ubuntu] no such partition. grub rescue -- need to restore regular grub screen

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http://ubuntuforums.org – Hi, the other threads I've seen about this were about deleted partitions. I deleted a partition but I still have active linux And windows partitions. Is there any way I can get back to the grub screen for my working partitions or do I need to boot from a disk? (I don't have it with me.) Thanks! PS chainloader gets me "unknown command" (Hardware)