It's not your fault...They come with tags saying they are indoor trees. I've personally not seen anyone keep one strong and healthy indoors. But, Don't let that be discouraging. Let this just be a stepping stone into one amazing hobby! Now, let's do some research as to what trees you are comfortable tending...with what you are able to provide for care.
This was kept inside...So assuming you may not have an outdoor space? If that the case...then, you need to look into tropcial trees. Anything for cold hardy zones need a dormancy period. You could benefit from filling out your profile information so ones could better assist you in the future as well.
But...this tree, as you surely guessed by now. Isn't going to green up. It's gone. But...Most times unless you buy a juniper which is pushing new growth. You could easily purchase a dead tree and not know it. They hold their green for a very long time...before turning this shade you now see.
Look into ficus...They can be kept indoors. If you have no access to an outside patio. Then look into styles...you don't have to have trees that look alike. There are Banyan, sumo, neagari and others that can be one species...allowing different looks with the same species. Keep that in mind too. But if you have a patio or outdoors space...the world can open up to more possiblities. Welcome...and don't be discouraged...