removed location assignments dialog

It could probably use some more smarts. I believe this dialogue box should only come up when the part is different, and is basically asking to remove the constraints since they will no longer be valid.

The constraints are stored in the ASCII file .qsf. If you've deleted the pins in the project and saved the project, then they've been removed from the .qsf and they are lost. If you still have a fit database, you could go to Assignments -> Back Annotate Assignments and choose Pin & Device(although this will put you back with the other speed grade). If you don't have a fit design, and don't have the .qsf, then they are gone. You can probably get them from the .pin file of the last compile, but it won't be in the syntax the .qsf uses.