Resharper move line up down not working

Alt+Up is not a ReSharper shortcut to move a line. It most likely belongs to the Productivity Power Tools extension, that has a feature to move one or more (selected) lines.

Personally, I don't like this feature in PPT, since it will just move the line(s), regardless of their scope, causing compilation errors. I much rather use ReSharper's feature of moving blocks of code up or down, by pressing Ctrl + Shift + Alt + ↑/↓ or ←/→ - when on the beginning of the line, it will move the entire line or block of code, but can also be used to move entire methods, change the order of parameters, etc.

I ended up resetting my Resharper shortcuts. Then when prompted with the dialog, chose Use Visual Studio Commands for the Alt+Up & Alt+Down shortcut.

You could also set this manually in Tools > Options > Environment > Keyboard. Search for "MoveSelectedLines" and then assign Alt+Up/Down to the appropriate command.