Alive is an adjective and means “living” or “not dead,” but we do not generally use alive before a noun.

• The lobsters in that tank are alive. Not, The “alive lobster”
• Luckily after the hurricane my tomato plants were still alive.

Live is an adjective and means “living” or “not dead”

• We bought live lobsters at the fish market.
• That truck is carrying live animals.

Died is the past tense form of the verb die, which means to stop living.

• Frank said his pet bird died.
• JS Bach died in 1750.

Dead is an adjective which means “not alive.”

• I pulled out all of the dead plants from my garden.
• I found a dead mouse in the basement this morning.