Help! Can't read mail in Mavericks

macOS & Mac Apps
Hi, I updated to Mavericks today. Everything went well and i even updated my voices that i use with VO, however something has gone wrong with my mail. It opens, that is it loads the program and starts to pull in mail, only the user interface with menus, tool bars, mailboxes and whatnot isn't shown so i can not read any mail. I have tried repairing permissions and that speeded the rest of Mavericks up but mail still doesn't open. What could be wrong and what can i do about it? If it takes a new installation to fix it how do i make certain to get everything back that will be wiped as a result of a clean install? Very thankful for answers of any sort. /Krister