I wan't to start playing ranked games, but since I don't have a team and I'll probably find a lot of trolls and unskilled players around 1200 ELO on solo queue, I'm afraid I'll get unlucky and see my ELO sinking...

So, if I regret going for solo queue ranked, is there a way to reset my ELO?

No, aside from waiting for the 'soft reset' that accompanies the end of every season of ranked play. It's pretty normal to sink down to 800-1000 Elo or so if you jump into ranked pretty quickly after hitting level 30. It's up to you how much it matters - personally, I really don't see it as a big deal. Any really good player would think my barely hitting gold at 1500 on an account or two is laughable and call me bad and not see a whole lot of difference between me and someone who's 600 Elo; it's all relative.

How does this soft reset work? How much "reseted" is the ELO by the end of every season?

bump

No there is no way to reset your elo. Also for a soft reset they use a formula that bring people closer to 1200 but without putting them there. For exemple after a soft reset a 600 elo could be around 800. Also it's always possible to climb elo. Many player have proved it by dodging until they reach 0 elo then climb back up to 1400-1500.