Why is the SRS light on after a wheel alignment service is done on your 2000 Honda Accord EX?
Possible air bag system malfunctioning. Take the car back to where the work was done, and have them look at it.
The alignment service was just a coincidence. This is a known problem and Honda issued a TSB on this.
Simply take your car to your local Honda dealer and tell them about the SRS light and remind them that there is a TSB on the issue. Your dealer should replace the OPDS sensor at no charge, regardless of age or mileage, as a goodwill gesture.
I had this done recently and it is has worked beautifully.
Normally it indicates you need an oil/filter change. It can also mean you need other service such as a cam belt replacement at 90,000 miles on your Honda Accord. Look in your owner's manual to find out what service needs to be performed at the mileage you now have. Your Honda has an interference engine so if the belt breaks serious engine damage will occur. Do not ignore replacing the cam belt at 90,000 miles.