I have had the occasional fish die, and it was no problem removing the plants from the tank, rinsing them in de-chlorinated water, then putting them back in the tank.
I agree with LindaRuth about finding out whether you had any contamination in the water. I suggest the same as she does, but change the water anyway. I hope you are using de-chlorinated, fresh water and "aquarium plants". I also suggest you get yourself a Ph aquarium water tester and test the water once a week; all instructions are contained with the testing kit.
I'd also be curious about the results of the water test, if you decide to do it.
Good luck.