Trouble with Bootcamp on Mac Pro (2010)

Hi, I’m looking for help in fixing an unseen partition. I tried to resize it using disk utility (worked previously) and it disappeared. Now Bootcamp doesn’t show up in finder, at machine boot, or in disk utility. I followed LonerT advice and did the testdisk quick search and went through the gdisk steps but I got an error at the end of GPT steps saying “Unable to open device ‘ /dev/rdisk0’ for writing! Errno is 1! Aborting write!” I’m stuck and I don’t know what else to do. Can someone please help me?