You have probably overwatered your pots...

The gnats are probably fungus gnats, most abundant where their larvae can eat lots of fungus. The thread-like worms are probably nematodes, and the ones large enough to see with the naked eye need a very wet environment to survive. Neither one is more than a nuisance, but, as Moon_grower says, they are a symptom of overwatering. Try to water thoroughly, but let the top cm of compost dry out between watering, and don't let any saucers sit full of water. If the soil is really peaty or muddy, sticking something like an ice pick down into the soil in a few dozen places and wiggling it slightly should also help, by aerating the mess.

thank you,so pleased its not serious .

Well, as for it not being serious, some flowers suffer badly from overwatering. My petunias had many problems a few decades ago when I had to find this out the hard way. I'm afraid that everything got underwatered for a few years after that! : )