Dinarina,
If you didn't find a headstone and there is nothing in the MI book (I presume it is "The Upper Ward of Lanarkshire" book, if it is, then the transcriptions are mostly pre 1855) and you have looked around the cemetery yourself, then the only thing left is to contact Bill Stanley at South Lanarkshire Council Cemeteries Office in Blantyre. (
www.southlanarkshire.gov.uk ) I am 99% sure that there are no burial records for this time period at Wiston and Roberton but check with them anyway.
Even in the Old Parish Records the death and burial records for this parish are poor.
In book one of the microfilm - 660/1 - There is a list of deceased person of the parish from 1689 through to 1701, all on one page and almost impossible to read, with only the name of the deceased given.
Also in book one there are deaths from 1746, virtually impossible to read, many names but written in a tiny, cramped hand with little or no information, they finish at 1772 and as far as I know there are no other records.
Looks like a dead end I'm afraid

Lodger