Engine tickover sticking on 4000 revs on renault clio campus sport?

I have a 2006 renault clio campus sport and it recently had a flat battery. After charging the battery and fitting it back on, the engine tickover is sticking on 4000 revs and will not come down. I did not switch on the ignition for 30 mins, once refitting the recharged battery, but his also did not work. Has anyone got any ideas how to solve this as it has been off the road for 2 weeks now and I cannot afford to take it to a renault dealer.