Impossible to answer without the serial number. You can, however, call Ruger or visit their webiste and find out.
Ruger.com has sn data on their website. Once you know how old it is, value can be estimated.
Ruger has extensive serial number data on their website.
You can find serial number data on Ruger's web site
100-1000 depending on specifics
You have a .44 Magnum Ruger Super Blackhawk, manufactured in 1978. If you had a question of a different nature, you'll have to clarify.
50-500 USD or so
100-1000+ depending on condition, accessories, etc..
50-1500 usd
Extensive sn data is on Ruger's website. 100-499 or so
100-400 usd or so
400 or so
100-1000 USD or more depending on specifics