Is your computer working but it's slow? If so you likely have a hardware or software issue.
For most people it will be a software problem. Either a program is using up your network bandwidth or overloading the computer's resources. Such as the processor or the disk drive. Worst case may be a virus or malware.
Don't overlook hardware though. If the processor gets too hot it will throttle down to much slower speeds. This happens when stuff accumulates on the processor's heat sink. Hard drives get corrupted, mainboard components fail also.