Xcode asks for codesign keychain pw

I can no longer build to my iphone 8 plus because I get asked for my codesign keychain access password and I apparenly do not know the pw. I was able to build to this iphone fine as of a few days ago. I am running Xcode 9 on Mac OS Sierra. IPhone is running ios 11. I can build to the simulators. Any help would be greatly appreciated. Thank sin advance Jim Allison