When i plug in my bass guitar into my amp it just makes a rapid thumping noise and makes no sound from guitar, but when i plug in my electric guitar it works just fine. Can anyone help?
A process of illumination is needed here (throwing light on the problem...).
You need to establish first if it's actually the amp or the bass. You've got half way there, as the guitar seems to work with the amp. Next to eliminate is the bass, by plugging it into a different amp. If it still doesn't work, then chances are it's the bass.
You've already (maybe) eliminated the lead (cord, cable), by using the same one for each, and if so, and it worked with guitar, it's not the lead. Even so, try another lead with each, so you know.
If it comes down to the bass only that doesn't work, it's more than likely the jack socket in that bass. Needs taking out and checking and re-soldering. Often a solder joint looks fine, but has become what's called a dry joint, remedied by re-soldering.
Check if the bass has problem with the jack output (it's one of the most common things to break on electric instruments). In that case you'll have to solder a cable or two.