The foremost, but sometimes overlooked option. Checking your network connection. If you are listening to Spotify music and it suddenly cut off or if you press play but nothing happens, it's most likely Spotify Web Player Not Working because of your internet.
First of all, we should try browsing other websites. If they seem rather slow, check your Internet speed.
If nothing opens, go to your system icons. They should be located in the bottom right corner of your taskbar. Right-click the Wi-Fi or LAN icon (depending on what you are using) and select Troubleshoot problems. If you are using Wi-Fi a common problem the troubleshooter can solve is the default gateway not being available. However, if you get the message that the DNS server is not available, it's time to restart your modem. If that doesn't help, you can flush your DNS.