I have a problem with my window i put it down one day and it fell down inside my door panel the side that is suppose to be under the rubber.

If your careful you can get the door panel out of the window trim at top with out breaking it. Hooter day is best to do it as the plastic panel is more pliable. Once out wedge it back some and pull the trim out. This will give you a good inch plus gap to work threw. Most like the cable has wrapped around it. Flash light to see it and bent coat hanger, long screw driver or bar. You should be able to get it open.

I recently purchased a 2008 BT50 dual cab then 2 days later we had 500mm of rain and of course it leaked :( I had about 80mm of water on the drivers side floor and 30mm on the passenger side floor. I stripped the interior out of the car and started hosing the outside and watching where it was coming in. I took all the windscreen surrounds off and the cowl panel off below the screen there was no water coming in from that area. I had taken the gutter seals off but left the door seals on so the water was running down around the outside of the seals (with the door shut) and out at the bottom. From inside near the drivers side kick panel I could see water coming through seams in the metal work and when I took the door seal rubber off the body on the car I could see water was getting in at the top of the door seal rubber going down the front inside edge of the rubber and getting in through the seam where the rubber push's onto the body of the car (first problem). I took all the door seal rubbers off and run a bead of non corrosive silicon inside the cavity and pushed them back on. It seemed to have fixed the problem I dried the carpet and put it back together..Two weeks later we got another 325mm of rain and it leaked again :( not near as bad this time. Looking at the bottom of the door where the door trim meets the door I could see water coming from behind the trim and then into the car. I took the door trims off and could see water gets in when the window is up (all cars do) and is supposed to run out the drain holes in the bottom of the door but the water was dripping and splashing up to the back side of the door trim against the sheet of plastic that is supposed to seal against the door with the black mastic (it doesn't) and running straight into the car. I cut some plastic and siliconed them onto each opening on the inside of the door frame and then put the factory piece of plastic on as well (properley this time) as a backup.
So far so good.

Window regulator or cable, depending on what you have

You remove the inner door panel to gain access to what
broke

Wether you can fix it, depends on your own skills

Not fun ,but I would never recommend anyone but you
doing it

Not the job repair shops like & in most cases only put
broken parts back on & 4 days later it falls down again

Don't know why they have always done that, rather the just
fixing it the first time

you have to remove the door panel..unbolt the tracking from inside the door..slide the windows back inside the track rails....push window all the way up..tape the window so that id does not fall back down or have someone hold window up while you rebolt the track to the door.replace door panel....the tracks move over time and that it why the window fell.

thw window either came off the window slider or the slider bracket, this can be determined by removing the door panel. this could also be cable driven and the cable has disconnected or broke, can also be determined by removing door panel.

Start by taking the door panel apart, the cable window regulators are not too complex and can be purchased aftermarket. More than likely a cable is broken.

It is most likely a rod has fallen off inside the door. You may have to use a coat-hanger to read down inside and pull back on door latch to open it up.
Then after it is opened, remove screws on inner door panel, remove window/lock controls, take a big flat-head screwdriver and gently pry next to the plastic tabs holding on door panel. Remove door panel and put window back on track , and replace or reattach door handle rods.

You are having a problem with the "window regulator" remove the door panel, see if the window regulator bolts fell out. they are usually in between the plastic door covering and the door or inside the door on the bottom. they are four bolts that a 10 mm wrench fit, they are short about 1/4 of an inch long, if they fell out you can simply put them back in (I recommend using lock tite on them) These bolts are located in the middle of the door a little towards the front. If your bolts are still in place you probably need a window regulator.

You'll need to remove screws that are by the door handle, arm rest, under door and side of door and then gently pull back on the panel as there will also be retaining clips attached and you don't want to break them. You'll need to lift the door panel upwards in order to get it off the window ledge. If needed, you can pull back the weather seal (can't reuse it, but it's not that important) and you will be able to access everything inside the door

take off inner door panel, lower track and put the window back in. If parts on track are broken buy new ones. Use urathain to reinstall window.