This Link to Microsoft should set you right up.
Pretty much everyone had to redo the DirextX thing several months back.

With the release of TBS expansion last week, you might have a broken UI, even tho you don't own the new expansion. This only applies if you are using a custom UI. You are OK if you are simply using the default UI.

If you are using a custom UI, even if it's just one piece, and you can't load past character screen, then:
go to your EQ Directory
find file UI_Dagger_seventh.ini
look for the line "UISkin=SomeSkinName"
change whatever text is at "SomeSkinName" to "default"
it should now read "UISkin=default"

Just patch the DirextX for now.
I wouldn't worry about the UI problem unless it doesn't let you in. Many people can get in the game with the broken UI's so can change to default in game if need be. It's easier. The above was only if EQ isn't getting past the char select screen.

"Trying is the first step towards failure"