There could be many different reasons why you feel you didn't end up with the results you were hoping for from University. However, this doesn't always mean you need to give up on your dream job; there can be ways round a disastrous or less than outstanding degree grade.
Statistics from the Association of Graduate Recruiters state that there are, on average 69 applicants for each graduate job and that 78% of leading employers will only interview graduates who achieve a 2:1 or higher. Don't panic however as these results don't apply to smaller companies who are likely to look beyond your university result in favour of experience, personality and what you can bring to the company. It can be personal and professional achievements that will make you stand out from the crowd of university graduates, especially if this is not your first job after university.
Ask yourself why it was that you struggled to deliver at university, it could have been that you just didn't enjoy the subject area and if that's the case, start looking for something that will give you a sense of fulfillment and not something that will make you unhappy. Be realistic with salary expectations and be prepared to start at the bottom and go that extra mile with your employer. It's much better to demonstrate in person why you a good employee than on paper and you're bound to pick up relevant skills and experience along the way which will help with your future search for your preferred graduate career.