Macbook Pro not Booting, stuck in utility mode.

I have been experiencing some problems with my Macbook Pro, in regards to the speed of the laptop slowing down, which increasing got worse to the point where Safari would freeze and stop responding, I would then have to force quit and reopen.

Two days ago the same thing happened with Safari but I couldn't force quit and the curser would change to the spinning beach ball and nothing would happen, so I did a shut down the computer with the power button and restarted. However it did not boot and went into utility mode.

I took it into a local authorised Apple service provider and they have stated in a summery report, "Diagnosed the machine, no hardware issue has found. AST test passed, No MacOS in the machine"

On the phone they stated that i have 0 data on my hard drive and there is no operating system and that I have somehow Wiped it.

Surly this is not the case, how can I have no operating system or data?

Any advice on what I should do? or is Data recovery my only option, Since It is not backed it up.