Yellow stem base
 

I've had this orchid for a month or so and I noticed that the air roots are dry and not green but the rest of the roots are okay... Also the stem base of the orchid has a little brown on it and is turning yellow and the petals have transparent spots
Can anyone help me save my orchid from dying?

A picture of the whole plant would be really helpfull.
From the photo you've posted it seems the medium and aerial roots are too dry.

Problem
 

Here a picture of the plant.. As you can see one of the flowers is dying
How can i bring thw aerial roots back to life?

I presume you've bought it already in bloom. Flowers, like the older leaves (in the bottom) also die.
You photos are not very sharp/nitid so I'm kind of guessing.
As I told you the medium seems too dry, as well as the aerial roots, while the ones under the medium seems to be pale green.
Your orchid is a phalaenopsis. Their roots, when dry, are silver but when you pour water on them they become green. As they are drying the green becomes light green and, finaly, silver. When you notice that the roots in the upper half of the medium are silver then it's time to water again. Depending on your conditions and type of medium it may change but, as a reference, the usual is once per week.
Don't ever let the pot sit in water because it leads to rot.
Some people repot as they buy them because commercial growers, in order to keep humdity in the pot, use sphanum moss to retain water/humidity. This causes root rot so people repot them and replace the medium by something that drains water easily, such as bark. Roots need water but also air circulation so this material is a good bet.

I'd sugest you to read this thread. It has a lot of information.

I water the orchid once a week as i read fearing that i would over water it ... If i understood correcly you are saying that the plant doesn't receve enough water
It's quite hot in the room where I keep it because we use wood to keep warm during the winter so do you think that's the problem?
This orchid really means a lot to me and I'd do anything to save it

Does this picture help? The roots outside are a bit yellowish some of them are a bit brown/black

This orchid looks like it is potted in bark, which is great - much easier to not over-water it. If the room is hot, it's also dry. You can water more frequently. Best way to water it is to hold it under the faucet, let water run through the pot. Then let it drain before putting it on a saucer or other "table protection" - it should not sit in water. By letting the water pour through the pot, you pull air into the root zone, and that is what it loves. Use a wood skewer (or pencil) to test how wet it is under the surface (there is a "stick" on this forum on using that method) It doesn't want to get totally dry - it is the wet-dry cycle that it craves.

Personally I don't think that the yellowing is a problem. It might be simply that the bottom leaf is on the way out over the next few months.
As for flowers dying, they have a limited life. It's normal at the end of the blooming to drop flowers.

As for watering, as you have it in a transparent pot, you can see the colour of the roots. Water it until the roots turn green, then drain and leave it till the roots turn silver grey and the medium is dry.

Good advice on water, yellowing ad flower aging already given above.

More advice on water - many Phalaenopsis orchids such as yours are sold with a shot glass for watering, or advice to water with ice cubes. NEVER water this way, it will usually lead to inadequate watering or possible root damage from the ice. If you feel compelled to use a shot glass or ice, pour yourself something strong in the shot glass, pour it over ice in a larger glass.

Water always by running plenty of water over the roots and into/through the bark. Don't water again until the plant indicates it is time (silvery roots, etc.). With Phalaenopsis, the bark should be watered when it is nearly dry but not quite (cool to the touch but not wet). Also, never mist the leaves, and avoid getting the crown wet while watering, as this encourages rot.

Thank you these are really good advices and I will definetly try them :) this is my first orchid so I'm kind of lost here haha