Roundup. If you need a weed cure, it's definitely roundup. You can get this at almost any Home Depot, and probably Lowe's. It's a miracle killer for weeds.
Just spray your lawn and all your weeds will go away. We had the EXACT same problem as you. 2 to 3 foot tall weeds just overtaking our lawn. My husband sprayed some roundup, and in a week or so they were all dead and gone. Now we have a perfectly nice lawn!
Mind you, you need to spray them before they are even 3 inches tall, otherwise you may not get very good results.
Good luck with your lawn!