Just check the bearings haven't gone - 1. Is it noisy(er) when spinning? 2. Open the door and put your and just inside the uppermost part, try and lift it a little. 3. Spin by hand, is it rumbling?...spoke to soon fellas.....the belt just came off again and is torn......ordered new belt....at least I know how to fix it now when it arrives.
2 - The inner drum (the shiney silver drum) and the outer drum (that you can't see) should move as one, if there feels like there is any clicking or free movement then it's the bearings. ! & 3 - it's the bearings. If the bearings have gone it's likely to have thrown the belt off for with excessive play.
If you want my opinion as an ex-domestic appliance repair guy - if it's the bearings on an Ariston I'd take it down the scrapyard and buy another. The majority of washing machine manufacturers are living off their past name, for instance Hotpoint, Creda, Cannon, and Ariston are (were? It's been a couple of years) part of the Merloni group in Italy where the quality dropped right off, even if they still have a sticker of the union flag on and says made in Britain, it's still Italian quality manufacturing techniques/fabrics involved. The only manufacturers I'd recommend are Bosch (group, so include Siemens and Neff), LG, Samsung, AEG (but no longer Zanussi which comes under the AEG umbrella), and maybe, just maybe, Whirlpool. All the others have sold their soul to the devil. Just saying.