Firstly, my deepest sympathies to the families and friends of the victims.

Now, it's relatively clear where the aircraft is. MH370 is at the bottom of the Indian Ocean. They haven't found it yet because the Indian Ocean is big, deep, and has relatively swift currents (for an ocean).

Do you remember Air France flight 447? By comparison to MH370 that flight crashed "just off the coast of Brazil," and with AF447 they had the advantage of knowing almost exactly where to look because they found floating bits of debris and bodies very quickly. Even then, it took almost 2 years to find the main wreckage of AF447 on the ocean floor and recover the "black boxes."

The search area for MH370 is many times larger than the search area for AF447. Searching for a plane ~14,000 ft under water (~10x the height of the new Freedom Tower) is slow and difficult work.

Sadly, it will probably take a while to find.