Can change position of midi notes?

In Reaper is it possible to change the position of the midi notes? I mean for example the B1 note above the C2 note. Thanks in advance.

I want to reorder the piano roll. I have already changed the name of every midi note, but I want to reorder them.

Not in the Piano roll, no (but it has been requested many times). Meanwhile, as James HE said, you could enter the names you want, in the order you want in the piano roll, then use a plug-in (e.g. ix_keymaps or codeFN42's NoteMapper) to convert those notes to the ones that your MIDI plug-in expects.