My money tree is dying quickly, not sure what kind of disease or issue it has.
It had root rot of like a year ago and I replanted and somehow it survived. Since last 2 months it started with yellow /brown spots and loosing all leaves.
What can it be and how can I help this plant to revive again if possible?

What direction do those windows face?
Are the blinds always open or closed?
How often do you check the moisture?
How do you know when to water?
Does water come out the bottom when you water?
Does it sit in water?
Have you fertilized it?
What did you use, how much and how often?
The new shoots at the bottom look healthy, so maybe they're just taking over from the old stems.

Hi & welcome! The soil looks very dry for an aquatic plant.

Thanks CalPolygardener, my answers:

CalPolygardener said: What direction do those windows face? south
Are the blinds always open or closed? Opened every day during the day
How often do you check the moisture? Once in a while, maybe every 2 weeks
How do you know when to water? I never know , last time almost killled it with too much water, so now try to water once a month
Does water come out the bottom when you water? Not too much
Does it sit in water? No
Have you fertilized it? Started in December with liquid fertilizer
What did you use, how much and how often? Miracle gro tropical plant food, follow the instructions( 4 pumps in 1 litre)
The new shoots at the bottom look healthy, so maybe they're just taking over from the old stems. Now leavea at the bottom are having same issue , even one of the stems feels hollow but its green on top

Hi purpleinopp and thanks.

purpleinopp said: Hi & welcome! The soil looks very dry for an aquatic plant.

Just watered it today with fertilizer as well (miracle gro tropical food) . One of the stems feels hollow in the middle but it's green at the top

Hopefully it was just thirsty.

Start checking it once a week. Stick your finger in good and deep or use a small stake to see how deep it's moist. You should feel that it's 'kinda moist' about an inch down when you need to water againIn a South-facing window it should need water more often than once a month. When you water make sure that a bunch of water comes out, not "not too much". A thorough soak.
Move it as close to the window as you can. They want some actual direct sun on their leaves at some time during the day, especially as far North as you are.
I think it needs more light and more water. Hold off on the fertilizer until it starts looking better or Summer, whichever comes first.

Thanks very much, CalPolygardener, will follow your tips and see if it survives. Scared to overwater again, because I took it out of soil and roots were still moist.
Also forgot to mention, I've seen some little black flies around the plants and trying to make them go away with vinegar but does not seem to work. Will buy the yellow sticky sticks.

I'm pretty sure it would benefit from a larger pot, too.

See if you can find Mosquito Bits. It's a bacterial disease of flies and gnats and will control your Fungus Gnats.