If you are connecting to your network via wifi ping spikes are very common and can't really be fixed since most are caused by interfering wifi signals from outside your house.
If you are using a ethernet cable it depends where the spike is. You might find it with a tool called pathping but you may also have to run tracert and ping the nodes yourself. The only ones you can really fix are if there is some issue with the router or the connection to the ISP. Hop 1 and hop 2 in most tracert. Ping spikes far into the path could be in other ISP networks even. You can only really get something fixed in your house or in your ISP network.