First try restarting the phone and reboot the laptop. (turn them both off and then back on) Next make sure that the internet connection is working on the phone itself.
Note: If you are using your carrier's/service provider's data through a data plan, this could be your problem. You may have either had your speed severely reduced due to usage, or had your data cut off for the same reason. If this is the case, you would have to contact your carrier/service provider about resolving the issue.
Now if the data is working, then, after clearing out all connections, try the following. On your phone go to...
1. "Settings" and tap "Wireless & Networks" and then tap "More".
2. Next tap "Tethering & portable hotspot" and then tap "Turn on WiFi...