Hii Vivek!
There are in total 10 isomers possible from c4h8o which include aldehyde, ketone, alcohol and ether. Talking only about  acyclic alcohol and ether, then there are  five possibilities. They are Crotyl alcohol, 1,2 epoxybutane, 2,3 epoxybutane, Ethyl Vinyl ether, Tetrahydrofuran. Try out the structures.
Hope this helps.
Good luck!