brown spot on leaf of Paphiopedilum
 

I've had this for about 1 year. Not only is it not growing new leaf (the new leaf has been that size for months). The leaves are now turning brown.

What's wrong with it and what do I do?

thank you!

I had the browning happen to a few of mine that were kept too cold. They didn't seem to be able to tolerate temperatures below 60F.

Doesn't look good. Would gently take off he brown leave and check the root system and may be repot into a medium that does not hold too much water With spring on the doorstep you might be able to grow new roots so it can recover

It is very hard to diagnose problems from photographs, but the first thing I noticed was that the potting medium looks like potting soil, so unless you barely moisten it, I'd bet the root system is quite poor, and that could lead to all of the issues.

My first thought was same as Ray's. Hard to tell from the picture, but the medium looks either like potting soil, or very broken down.

And as Aliceinwl says... at what temp has it been kept? I have a couple where temp was below 60 at night for a month or more, and the older leaves looked the same.

I'd get it out of the pot and see how much viable root is there. My guess is likely not much. Repot in better media. Can't hurt, since it's on a downhill slope at the moment.