Ways to straighten a tie rod:
Turn it and use a jack to push it back up, like has been said.
If you have a winch, run the cable around the axle housing and then to the tie rod, and pull it straight.
Find a log (or pipe), drive the front tires to the log, run the winch cable (or chain) under the log and up to the tie rod, then drive forward slowly climbing the log. The cable will be pulled down, straightening the tie rod as you begin to climb the log (or pipe).
Take it off and straighten it by hooking it on something, then put it back on.
Once the tie rod is straight, it will be weaker. You can weld a piece of angle iron along it, which will make it pretty strong, or get a new heavy duty tie rod.