Assuming those channels are part of your package, you can follow the TV Care menus to resolve "missing channels" issues.
Look under under Home > Help & Settings > TV Care > Missing channels.
VM's help page has some further advice, and links to the channel listings here
All that assumes of course you can get your box to power-up, which is evidently the more serious fault. You can try unplugging it from the mains for 10minutes and retrying, assuming all the connections are finger-tight.
If you still have no service, it's time to call into TV faults and report your issue. Forum staff work their way through the posts on here, but that can take a few days.
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