Engine won't crank sometimes ??

Replaced the starter relay on my 2000 V70 XC, but am having the same intermittent problem of the engine not cranking over. This problem seemed to start when I inadvertently let the battery run down and needed to jump start the car. On several occasions now the wife was unable to start the car, then after driving there to check...it magically started with no explanation at all. This went on for a few days but it now will not crank no matter how long I let it sit in my garage. Having replaced the battery did not resolve the problem either. Already tried to move the shift lever back and forth and put the alarm off and of numerous times in case it was a problem with the disabler (which I'd love to locate). Would love to hear if anyone has similar trouble... My wife is happy to be driving my BMW 540 wagon but I'm not so happy right now to be stuck in my un-renovated 1965 Austin Mini. Any help or comment would be greatly appreciated. Cheers/Chris

starter motor solenoid?

Automatic for the people 

Is your car an auto? If so have yopu tried starting in Neutral or wiggling the selector as you crank? Could be contacts on PNP switch. With engine off pull trigger on selector and pull/push lever through it's full movent about 30 times. If you have a keep fit gearbox then you will be looking at the immobiliser or as the previous post said the starter solenoid. If you can see it, it should be a small cylinder like object on the side of the starter, give it a few taps with the shaft of a hammer. Hope it's a cheap/quick fix Lee

I had the same problem on my 2001 V70 and it was a corroded connection on the starter motor solenoid. Cleaned the connection and gave it a good of vasaline and had no more trouble. Best of luck Jim

Thank you for the replies