2007 Vauxhall Corsa drivers door

cannot open the drivers door from the inside, door latch does,nt seem to be broken, have to wind window down and open from the outside, probaly something so easy l,m missing it, my 6yr old son said it could be the child lock but the drivers door does,nt have a child lock, he,s on the right path l feel, l,ve probaly pressed a button but dont know which one as l dont have a manuel, can somebody please help, very frustrating.