It has been my ultimate aim to get into an IIT!

But I dont know what happened I couldnt do well yesterday!

Is repeating the only way to get into IIT?????

If it is so then sure I will!

But can u suggest me some books I should follow?

Yes , if this is your ur ultimate aim then there is no other way .. but i think u shouldn't be so negative at this point of time.. so better  .. Now study hard and if you get decent rank thn take admission in some good collage instead of dropping.