Reviving a very poorly orchid!

[new plant lover]

I am new to looking after orchids but have started researching them a little more and would like to get into caring for them properly!

I had a pink Phalaenopsis as a present in august last year and it lasted about 5 months until the flowers dropped. I cut back the stem as someone told me to do so it could reflower, but saw no action for quite a while so I admit to giving up on it after that as I didn't know much about the plant then and I stopped watering it for a long time. However, I have noticed a new stem in the last couple of weeks and a new leaf (although the other leaves are all wrinkly and limp, and one is yellow)

I started watering it again when I noticed this (a couple of weeks ago) and today I have inspected the roots - which are a mess. They all look hollow and dead and I can't see how this poor orchid even managed to sprout a new stem. Is it worth trying to save? If so... how?!

I thought I was watering it just the right amount, but perhaps I have overwatered as the roots are all dead. It is in a light position, but not too light - I have many other plants near it that are doing fine.

Any help would be greatly appreciated!