Do-it-yourself fence repairs will save you a substantial amount of money in repair bills. Never attempt to push the fence post up straight without first digging the dirt out next to the post. Otherwise, you will crack the post at the base which could result in a larger repair project than was originally necessary.
Dig a 3 feet deep hole out around the leaning post with the shovel.
Drive one of the stakes 24 inches into the ground on one side of the fence post with the sledge hammer. Drive the other stake 24 inches into the ground on the opposite side of the post.
Pull the fence post up straight. Lay the level on top of the post. Move the post until the bubble in the level is in the middle of the indicator, confirming that the post is straight.
Attach one of the 1x4 pieces of lumber to the ground stake using the drill and a 3 inch wood screw. Attach the other end of the 1x4 piece of lumber to the fence post at a 45 degree angle with a 3 inch wood screw. Repeat this procedure on the opposite side of the fence post. Do not tighten the screws down completely.
Lay the level on top of the fence post. If the fence post has remained straight, tighten down the wood screws. If the fence post has leant, unscrew the wood screws that attach to the fence post and reposition the post.
Mix the bag of concrete with water according to the package directions. Pour the concrete into the hole around the base of the fence post. Make a hill around the base of the post so that water will run off.