08 sporster 1200 changed both front turn signal bulbs now they stay lit and don't work won't flash either side.what can I do or check

Check the bulb types. Were they single contact or double contact? If you use the wrong one it can cause your problem.

Both double contacts.red key on speedometer is on.should I replace all four bulbs and start there.

Bulbs should be 1057 or 1057LL, red key on speedo is security system. Check all bulbs to be sure they're good.

OK thank you very much for your help.

Do have a TSSM(Turn Signal Security Module), your signals are security indicators. Not sure if your model has it. Not only does your turn signals run through it, it also interrupts Starter and Ignition.
A buddy of mine had the schematic, and I figured how to make a TSSM test plug, it would allow testing of the bike to see if it failed, you could actually eleminate the system with this, and by adding a flasher, bike would operate normally with no Security.
This would allow riding till system is repaired, or till you could afford a new one, should they be outrageous.