Unlock the vacuum

Dear all,

Can anyone tell me how to unlocak a vacuum ? Because last time i run the vacuum and stop while running. When i do a
vacuumagain this morning, it says 

michaely=> vacuum;
WARN: Can't create a lock file - another vacuum cleaner running ?

Thanks for your attention and any solutions will be highly appreciated !

Cheers,
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| Michael Yeung                 |
| Alpha Network Shop            |
| Tel:(02)9413-3886        Fax:(02)9413-3617    |
| Mobile:0411-233-597            |
| mailto:michaely@alphanet.net.au        |
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