The first step is to remove the barreled action from the stock. Once this is done, remove the screws that hold the trigger assembly in place. There are two screws on either side of the assembly.
Once these screws have been removed, carefully lift the assembly out and take a look at how it is constructed. There are several small parts inside and it can be a little confusing as to how it all goes back together. The best way to approach this is to start with the trigger itself.
The trigger has two small tabs on either side that fit into slots on either side of the assembly. Carefully fit these tabs into their respective slots and then press down on the top of the trigger until it snaps into place.
With the trigger in place, you can now move on to the hammer. The hammer also has two small tabs on either side that fit into slots. Fit these tabs into their respective slots and then press down on the top of the hammer until it snaps into place.
The next step is to replace the sear. The sear is located just behind the trigger and is what keeps the hammer from moving when the rifle is not cocked. To replace it, simply press it back into its slot until it snaps into place.
The final step is to replace the safety. The safety is located on the right side of the assembly and is what prevents the rifle from firing when it is not supposed to. To replace it, simply press it back into its slot until it snaps into place.
Now that the trigger assembly is back together, you can replace it in the stock and screw it back in place. Once this is done, your Remington 700 should be as good as new!