No bootable device how?

@mohmmadfaza1060 you are really not giving us enough information here. We need to know the exact model number for your Acer and if anything happened to it or if this just all of a sudden started.

This error is usually caused by your computer not finding the OS. It is possibly due to a failed drive. First step to take is to restart your computer and press F2 to enter BIOS, then check to make sure that your hard drive/SSD is detected. If it is not detected you most likely have a failed drive. You can try to check the drive by changing the boot order in the BIOS to USB drive. Then get a bootable USB drive with some small Linux OS installed. Use that to start up your computer and see if you can now access your drive.

If the drive is detected in the BIOS then it is possible that your OS is corrupted you may have to re-install your OS.

This is all very generic until we know the exact model and what is going on with it.