Antinuclear test negative in 2017,but positive +++ n 2018,is it posible 2017 test was wrong,cud i hav had d disorder even if test said negative 2017?

Possible: you could have had a falsely negative ANA in 2017, but more often I see a falsely positive ANA than falsely negative. Presence of ANA is not diagnostic of any condition, testing method is important, titer is important, pattern of ANA helps and subset of antibodies that are also positive. Most important is your clinic presentation that determines whether this needs to be investigated further

YES: Lab tests are not always accurate; there are many reasons a result may be inaccurate. Whenever a test result does not make sense to me I tend to repeat the test and very often it shows that the first test was probably wrong. So yes, it is definitely possible that it was wrong, though there will never be a way to know for sure.