How can i "fish?" a wire from my 2nd level of my home to the first level going through my walls?

I need to run a cable or ethernet cable from my office up stairs to my modem in the living room. I really dont want to use wireless. Any help would be apreciated.

Yes there are bits long enough to drill through stud bracing inside walls, but I'd do a hole in the floor at the wall and use surface molding to hide a cable

This is a quick and easy job for an experienced remodel job. Locate where you want the outlet upstairs, cut a hole in the sheet rock that will accept the LV ring for your cable. Drill down through the floor plate inside the wall with a "Diverisbit" then cut a hole the same area in the wall downstairs. Attach the wire to the end of the bit and pull it up through the wall. Locating the holes and any wire or pipes or heating ducts is up to you.
If you need help, call a qualified professional remodel electrician.

It is almost imposable without cutting the sheet rock. You need a ten foot drill to drill through the roof, through the second story plate and through the first story plate, then you fight insulation and cross bracing in older houses.The best you can do is to run it on the outside wall or in the inside wall, or cut two holes in the wall.

Jim W gave you the only answer that makes any sense, and shows any experience doing this.

The Greenlee "Diversibit" is the best tool for the job, just be sure you purchase the grip/control handle for the bit, also. (And, practice a little, first - it's hard to get the hang of using this long bit without seeing the end of it without drilling out through your drywall.) You may need to purchase an extension, depending on what the distance from the wall opening to the top plate is.

The only things I can add, are: use an inside wall if at all possible [easier access in the attic (when you need to be up there), and no insulation to fight through in the wall], use a good stud finder to locate a position between two studs, and try to locate any electrical wiring in your way by using a good non-contact voltage detector.

Try to keep at least one stud between your cable and the electrical wiring (it limits interference with the communication signals), and cross any line voltage conductors at 90 degrees, for the same reason.

Go to the hardware store, get a wall-tape (or wall-snake) cut a small hole in the wall (careful not to hit your electrical wiring) (this is your 2nd floor). On the first floor directly below the 1st hole you cut a 2nd hole. securely tape the wire to the wall-tape and feed it down. Use plate covers to conceal the holes.

dont forget that u have to drill thru the bottom plate of the 2 floor..double plate of the 1 floor and the top plate.....and cut 2 holes in teh rock and pray u dont hit electric wires in the walls...might want to rethink the wireless...$39.00 router and ur there.....