Dear Swati,
The question you raised for advice is cryptic and is devoid of necessary details required for careful consideration. The term "ignorance of work" can be interpreted in different ways, viz., the person is ignorant of job knowledge and experience required for the job he has been recruited for. This might have happened due to the reason that he has been placed in a job demanding skills other than what the recruit possesses, or he has been recruited for the job without assessing his skill/knowledge for the job in question. In both of these situations, the HR department is to blame for its inefficiency, for which the employee concerned cannot be held responsible.
In the other case, you have not clarified what the person is doing while he ignores his job, viz., if he idles, incites his co-workers or other workers, or is absent from work, etc. Your warning letter will be lame and not very effective if issued.
However, a warning letter is suggested as below:
Dear...,
Designation: __________
Section: __________
Department: __________
It has been brought to the notice of the management that you have been ignoring your work since ________ and have been loitering while on duty. This has adversely affected production in your section and is affecting the discipline of the section. Your supervisor has advised you time and again against it but in vain.
In view of the above, you are hereby warned and advised to desist from these activities in the future. In case no improvement is found in your work and conduct in the future, the management will be compelled to take disciplinary action as it may deem fit.
HR
In case the employee comes up with a reply, please ignore.
Thanks and regards,
S.K. Johri