I agree with Sylvia. In a slow market there can be a shortage of comparable sales. When you say "there have been no sales" that tells me that you need a resourceful Realtor who knows how to get the information needed to help you get your home sold.
I would discuss your question with a local Realtor. You do not mention why you need the value of your home. There are actually different types of values for different purposes:
1. Appraised value, performed by a licensed appraiser, usually for a collateral for a loan. Usually based on historic sales from the last six months, plus changes in local market conditions, generally conservative to protect the interest of the lender
2, Replacement value - used by insurance companies to determine the cost to re-build in the case of total loss, such as fire. Recent increases in building material costs make this a concern for insurers.
3. Fair market value (FMV) - the price a willing and knowledgeable buyer will pay under normal market conditions - not facing foreclosure, must sell within a certain time frame.....only "normal" circumstances
4. Wholesale cost - the price an investor would pay, usually cash and can close within 30 days, with the purpose of buying either to flip or to hold for long term investment.
Hope this helps.