check the paper size settings...
Assuming it's A4 you're using, it presumably has the width as 21 cm and the height as 29 cm...
Can you set a custom size, and reverse this, such that it has a width of 29 and a height of 21 ?
It's probably not the real answer, but it might do as a workround. I'd be surprised if it's a hardware problem with the printer, rather than a software issue.
Perhaps you could try a system restore to before it started?