If my opponent targets my spell with Lilting Lullaby and I counter my own spell in response, can I still play spells?
Yes. Countering your spell clears it from the chain, so it is an illegal target when Lilting Lullaby resolves.426.1.a355.9.a.2359.3.e.2 Lilting Lullaby still resolves, but its counter instruction is ignored because the target is illegal.359.3.e.1359.3.e.5359.3.e.6 The spell-play restriction is linked to that ignored instruction through "its controller," so the restriction is also ignored.359.3.e.14359.3.e.14.a