The soil is fine I think, when I touched it, just a little bit of the soil sticks to my finger, it was bought about a week ago and watered afterwards, I also found a couple of little yellow leaves and got rid of them. Some ends of the leaves are a little dry and dark and I see dark spots on the plant.

What is the temperature near the window during the day? These plants don't like to get too hot or too cold, between 65 and 80 degrees.

What way did the window face?

Also does the pot Have drainage holes? How do you water it?

The greening and the browning of the spathe is normal, it happens with old blooms.

Are the brown spots on the leaves at the tips?

By the window it's 90 degrees, then I moved it on a table and it's 75 degrees in the room

It faces West

It does have drainage holes on a bottom and I watered it with half cup of water after I bought it and yes the brown spots are on the tips of the leaves with a little bit of yellow too

Half a cup isn't very much for a plant that size. Assuming the soil drains well, it's good to give a thorough soaking - at least until water drains out the bottom. Then don't water it again until it needs it.

Browning leaf tips are most likely from using tap water. Peace lily's and most plants are sensitive to the dissolved chemicals in our water like fluoride. To correct this use distilled water, rain water snow melt, or like I do water from a fishtank or pond.

Lots of people on here (including me) like to take their plants to the sink or tub then water them thoroughly untill it starts pouring out the drainage holes (I usually keep on watering for a few seconds after this starts, that way I know the whole root ball and soil got its share).

Peace lily's love water and can even be grown in the water. You shouldn't allow them to dry out between waterings.

A west window is too much light without any accumulation. Probably got way to hot! He seems like he should bounce back fine. Once you get the care down these plants are very easy to care for.

Good luck with him!

I watered it until the water came out of drainage holes and it looked great in a morning, thank you so much everyone for a lot of great tips!

Yay! That's great news. You'll like these plants. They really add a nice focal point to a room. As long as you water them regularly and don't over-fertilize, and keep them at reasonable temperatures, they tend to do ok.

As soon as you see a little "slump" in the leaves, go ahead and poke your little finger down into the substrate as deep as it'll go and pull it out. Now, rub your finger and thumb together. If you feel wet (like actual water) and not dry/crumbly, then don't water it and check to see if it is standing in water. If it is standing in water, remove it immediately and flush the soil thoroughly until you see water leaving the pot very rapidly and let it freely drain until it is done. If this does not perk up the plant after about 12 hours, you may want to remove the roots from the pot to let them air and check for rot.

If it is dry/crumbly on the tip of your finger and you can't feel wet, then....well, I guess the directions are the same....just for a different reason.

water thoroughly until water flows quickly put of the bottom letting all of the remaining water drain off.

If it gets VERY dry, you will need to soak the whole pot in water for about 30 minutes to rehydrate the whole rootball.