The bracket underneath my car broke and my seat ricks back and forth...do I need to replace the whole seat or can it be fixed? I have a 2000 honda accord ex 4 dr v6

You can take out the seat end weld it

There's no way to answer this without seeing the damage, sorry.

The entire seat certainly needs to come out to be inspected, and only then can a decision be made as to whether it's possible to make a repair by welding. Often it's possible to do so, but is impractical if the seat needs to be stripped right down. If the seat has any airbags built in (European spec versions have a side airbag) then the car battery must be disconnected prior to seat removal and precautions must be taken when welding to prevent the airbag from detonating.

In practice it will often be cheaper and easier to replace the seat with one from the scrapyard, but finding a good one can be a hit and miss affair. The V6 Accord tends to be driven by rather well upholstered drivers and 10 years of carrying that kind of weight will leave many seats with worn upholstery and saggy cushions. One other option is a lot more expensive but still might be preferable to fixing your own seat: you could source a near perfect seat from the UK. As we drive on the right (RHD), what you use as a driver's seat is a virtually unused passenger seat over here. If I'm wrong and you are in a RHD country then the advice still holds good: just search scrapyards online in LHD countries instead.