Motor wont start!

[LowchevyII]

so my car has been sitting for a while maybe about 6 months without being started...thinking it wasnt going to be sitting long i havent put any additives in it for long term sitting. Now i want to get the motor started so i know it runs so i can sell it. However, went to go out to start it this morning and it wont turn over. any ideas and or suggestions of what you may think it is (i know its vague) or any suggestions/tips on how to start a motor after long term storage?

thanks guys

jeff