When you say "half the value", do you mean "current market value" or a "previous sale price"?
By itself - - - it would have no effect and nothing to do with the resale value of yours. Unless your property is also a foreclosure. If there has been multiple foreclosures sold recently, and multiple current active foreclosure listings, of townhomes, in your neighborhood, then combined they may or may not have a negative impact on your resale value.
What affects the resale value of your property is the current market condition and trends, of multiple similar properties in your neighborhood (townhomes) and market area. Most likely, the overall market in your neighborhood/market area has declined over the past couple of years, similar to that of other market areas around the country. Mostly due to the increase of distressed properties (short sales, foreclosures) and increase in supply.
If you were to currently put your property on the market for sale, depending on when you purchased it and the amount of the purchase or mortgage, you may or may not find yourself "underwater" as they say. Where your current market value is less then what you purchased it for, or the balance of your mortgage if you have one.
In any case, the resale value of your property, or current market value, would most likely be determined by the sales comparison method, and current active listings among a long list of other factors, of similar properties, and analysis of market conditions and trends, for your type of property and overall market area.