I have a Bell 5900 pvr and am not with bell anymore. I am with shaw now and I am wondering if there is anyway I can reprogram it to work with shaw.

Nope, it is a hardware preventing such, mostly.

Nobody is openly re-writing software for provider DVRs.

The hardware can only tune satellite, and it does not use DCII security.

You cannot use the DVR as a standalone with a Shaw box either, it has no A/V inputs or video encoder.

Hi would it be the same for a shaw gateway pvr? was hoping to hook it up to vmedia?

As already stated, it's not possible in most cases due to hardware limitations. Even if it was possible, Canadian TV BDUs usually do not allow it and refuse to authorize a box they did not originally sell. The best bet is to sell the unit locally and put the money toward one designed for the new service. It might be possible to break even or come out ahead if buying used.

A few TV BDUs sell Android based boxes that can run apps and be used for other purposes. Even those are often modified in ways that make them useless for anything but the company's own service. A lot of BDUs now support other company's media players such as Apple TV or Android TV units but usually require at least one of the own proprietary units on the account. Third party boxes often have reduced functionality as well.

One company that does not require a proprietary device is Teksavvy TV. They use an app on generic Apple TV, Android TV or Amazon Fire Stick devices.