You need to comment your code.Even for yourself
hsp = 0;//horizontal speed
vsp = 0;//vertical speed
grv = 0.3;//gravity
walksp = 4;//walk speed
if (place_meeting(x,y+1,oWall)) && (key_jump)
{ vsp = -7;
}
and not
if (!place_meeting(x,y+1,oWall)) && (key_jump)
{ vsp = -7;
}