Reasons Communism didn't work is because people were increasingly dissatisfied with the following:
1.) There was no such thing as private property. If you owned land, a farm or farm animals, those became the property of "the people"...or rather the state. To add insult to injury, they forced you to work those fields and feed the animals they took away from you. Also, practicing religion was forbidden although many older people did it anyway in their homes.
2.) It robbed people of ambition and therefore the drive to work harder. Everyone was required to work. You either worked or went to jail. Sounds fair...even nice until you realize your job is never going to earn you any great luxuries, and it's not like you can become anything you want to be. The lazy bums at your job earned the same amount as you and no matter how badly they slacked off, they knew they weren't going to be fired. You begin to wonder why you're killing yourself when there's nothing special to achieve....unless you kiss the ass of Communist party members and become one of them. They got rich by stealing, through bribes, etc.
Many, many people worked for the Government and their job was to create a bureaucratic nightmare. If you came in to get anything done, it took months and they treated you as if they were doing you a favor you didn't deserve. Pretty soon even store clerks adopted this attitude because the store was owned by the state so there was no private business owner to answer to.
3.) Corruption was so high that you couldn't even achieve some of the most simple things without a bribe. Many parents bribed teachers for their children's passing grades all the time. If you wanted to get into a good College, grades made little difference. It was all about who you knew and who you could bribe. People wouldn't show up at a doctor's office without gifts....at least a bottle of vodka.
4.) Borders were closed and you were no longer allowed to travel to the west. If you absolutely had to go, you were forced to leave one of your children behind to motivate you to come back. If you decided to leave your family behind and escape, they would cease your property and interrogate your family. If you decided to return, you would go to jail for however long they wanted you there. No due process.
-Some guy on Reddit