If you are interested in what happened to MH370, it would probably be a good idea if you read all searches and studies that were made since it disappeared (the real ones, not the conspiracy theories, of course). The Wikipedia page on the topic is probably a good starting point.
Most of the evidence points to the aircraft having crashed into open ocean West of Australia.
The aircraft then disintegrated into many different pieces of various sizes, some of which kept afloat. Winds and currents then carried them away to the East coast of Africa (and islands on the way) where they were discovered, recovered and identified.
Given the great distances, and given varying sizes and shapes and buoyancy, not all pieces ended up in the same place, they were spread out over quite large distances.
While there was a lot of confusion initially on the trajectory of the aircraft (which led to searches in many different places), it is now clear that after turning back and crossing Malaysia, the aircraft then veered South, and flew for many hours before running out of fuel and crashing. This was estimated from analysis of ACARS data received by satellites, where Doppler shift and round-trip-time information yielded speed and distance (from the satellite). This has later been confirmed (with apparently higher accuracy) by analysis of disturbances in Wsprnet transmissions at the time.
The initial confusion, lack of transponder data, and limited radar data, means that initially, a lot of time was lost looking for the aircraft in places where it wasn’t. When it became clearer where the aircraft was, the possible area was still extremely large. While many overflights took place in that area, identifying relatively small pieces floating on the ocean, already dispersed over a large area, is very difficult. It’s not like there were full wings floating on the ocean with a beacon on them, or bright orange or yellow liferafts.
If you consider AF447, remember that in that case:
- The actual flight path was pretty well known;
- Their last known position was very close to the actual crash site (last position sent at 2:10 UTC when the crash occurred around 2:15)
In that case it still took about 36 hours to find signs of the wreckage, and it was already spread over 5 km. So you can imagine what happens if you get that area to search a week after the aircraft has disappeared, and the area to search is soo large that it’s materially impossible to cover it in a timely manner.
I believe there is still debate on how the aircraft “landed”, I.e. whether it was a somewhat controlled ditching (in which case most of the aircraft would have been intact and would quickly have fallen to the bottom of the -very deep- ocean) or if it really crashed (which means a lot more smaller pieces, but a larger possibility of floating debris), but in any case, the delay and the size of the area make locating any pieces in the open ocean extremely difficult.