they had better troops and material aid and they just didn't use them ???

They thought Chile was going to invade southern Patagonia, Argentina actually had planned to invade the southern part of Chile if the border negotiations didn't went their way, which is why they were keeping their elite and cold-weather warfare there. Doesn't justify sending young men to die in a stupid war, but it explains why the Argentine Army fought so poorly compared to their Air Force and Navy who actually caused problems to the UK.

junta's terrible management & the whole military was like that.

The entire army was practically corrupt, the air force actually hit some important ships with bombs, but they didn't explode due to poorly maintained equipment. They even tried to destroy the Royal Navy in Gibraltar using some left-wing guerrillas that the Junta had arrested. But I think they were caught by the Spanish police before they could act.

The whole war was badly planned because they thought that the United Kingdom would simply give up these random islands and everything would be resolved diplomatically. Most of these generals were imprisoned for this and for treating their soldiers badly, some of them literally had nothing to eat while they were freezing on the island, the Royal Army had night vision goggles, while the Argentine Army had nothing to see in the dark.