I assume that you have measured the voltage with no load, i.e. with the laptop disconnected.
If so, it is certainly dead.
Laptop power supplies are difficult and dangerous to fix. It may be possible to save a few dollars by buying a generic supply and fitting the cord from your broken one.
However, many manufacturers (including Dell) have special identifying chips in the power supplies, so you can't just supply the correct voltage.
This is real pain if it is combined with a badly designed connector, like Dell use.