help!flymo micro lite won't spin enough to cut grass or hovver!?

Hello I lent my lawn mower (flymo mico lite) to a neighbour a few weeks back as her grass was rather long (12+ins) and damp,so I advised her to strim it 1st,leave the rest to try and then mow it,but she didn't and went straight over it all. Although it was apparently working fine when she handed it back(I put it straight in the shed then),I went t use it for he 1st time since then today and it won hovver or cut the grass,just tries its hardest to move a bit!I tried cleaning the whole thing out with a brush,the filter looks ok and there's nothing weighing it down and changed the keys, but it just refuses to pick up speed.Is this probably caused by the dampness of the grass that time?If not,what's the likely and how can i fix it??Please help I love and want my lil Mowie back!!