No, seriously, stop for a moment and define it to yourself. I want you to come up with a serious definition, too, not "those assholes who hate darkies" or something like that. Come up with what they stand for, what they stand against, a serious definition of some kind.
Step Two: Determine if we've actually had a conservative government for any period of time since 1980 that have actually acted on the definition of conservatism.
I've posted this as a meta-message because you can get different answers depending on what perfectly legitimate definition of conservatism you adopt.
If you define it solely in terms of reactionary defense of the status quo, conservatism is politically dead, since the status quo has been, is, and will continue to never apply in our world. It moves too fast for that.
If you define it as isomorphic to the Republican party, then it has been in charge and is discredited... but I don't find this a very good definition, as we already have a perfectly good word for "Republican".
If you define it as involving cutting taxes, it has had some success, although only some.
If you define it in terms of libertarianism, i.e., "smaller government", then it has not been in charge since 1980. We've actually not tried "smaller government" in a long time. It's hard to even identify a year since 1980 where it was winning the war, let alone claim it has been winning since then.
"Conservative" and "liberal" are really such ill-defined constructs that using them seriously without defining them almost always indicates weak thinking. For example (and I'm not saying mattmaroon said this, it's just an example) claiming that "conservatives have been in charge since 1980, conservatives stand for small government, conservatives have been a failure therefore small government is a failure" is very bad logic because the meaning of "conservative" keeps shifting throughout the argument.
Social conservatism has had a much better run than fiscal conservatism or small government, which has had almost no traction since the New Deal or even earlier. A couple of years of exception, but even those years it was mostly lip service followed by expanded government.